diff --git a/mozilla/content/svg/content/src/nsDOMSVGZoomEvent.cpp b/mozilla/content/svg/content/src/nsDOMSVGZoomEvent.cpp
index 688ec08f465..b9c0946d61d 100755
--- a/mozilla/content/svg/content/src/nsDOMSVGZoomEvent.cpp
+++ b/mozilla/content/svg/content/src/nsDOMSVGZoomEvent.cpp
@@ -39,7 +39,7 @@
 #include "nsContentUtils.h"
 #include "nsSVGRect.h"
 #include "nsSVGPoint.h"
-#include "nsISVGSVGElement.h"
+#include "nsSVGSVGElement.h"
 #include "nsIDOMSVGSVGElement.h"
 #include "nsIContent.h"
 #include "nsIPresShell.h"
@@ -74,7 +74,7 @@ nsDOMSVGZoomEvent::nsDOMSVGZoomEvent(nsPresContext* aPresContext,
     if (doc) {
       nsIContent *rootContent = doc->GetRootContent();
       if (rootContent) {
-        // If the root element isn't an SVG 'svg' element these QIs will fail
+        // If the root element isn't an SVG 'svg' element this QI will fail
         // (e.g. if this event was created by calling createEvent on a
         // non-SVGDocument). In these circumstances the "New" and "Previous"
         // properties will be left null which is probably what we want.
@@ -87,16 +87,16 @@ nsDOMSVGZoomEvent::nsDOMSVGZoomEvent(nsPresContext* aPresContext,
           currentTranslate->GetX(&x);
           currentTranslate->GetY(&y);
           NS_NewSVGReadonlyPoint(getter_AddRefs(mNewTranslate), x, y);
-        }
-        nsCOMPtr<nsISVGSVGElement> privSVGElement = do_QueryInterface(rootContent);
-        if (svgElement) {
-          mPreviousScale = privSVGElement->GetPreviousScale();
+
+          nsSVGSVGElement *SVGSVGElement =
+            NS_STATIC_CAST(nsSVGSVGElement*, rootContent);
+          mPreviousScale = SVGSVGElement->GetPreviousScale();
           NS_NewSVGReadonlyPoint(getter_AddRefs(mPreviousTranslate),
-                                 privSVGElement->GetPreviousTranslate_x(),
-                                 privSVGElement->GetPreviousTranslate_y());
+                                 SVGSVGElement->GetPreviousTranslate_x(),
+                                 SVGSVGElement->GetPreviousTranslate_y());
           // Important: we call RecordCurrentST() here to make sure that
           // scripts that create an SVGZoomEvent won't get our "Previous" data
-          privSVGElement->RecordCurrentScaleTranslate();
+          SVGSVGElement->RecordCurrentScaleTranslate();
         }
       }
     }
diff --git a/mozilla/content/svg/content/src/nsISVGSVGElement.h b/mozilla/content/svg/content/src/nsISVGSVGElement.h
deleted file mode 100644
index b6e1e121e53..00000000000
--- a/mozilla/content/svg/content/src/nsISVGSVGElement.h
+++ /dev/null
@@ -1,95 +0,0 @@
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* ***** BEGIN LICENSE BLOCK *****
- * Version: MPL 1.1/GPL 2.0/LGPL 2.1
- *
- * The contents of this file are subject to the Mozilla Public License Version
- * 1.1 (the "License"); you may not use this file except in compliance with
- * the License. You may obtain a copy of the License at
- * http://www.mozilla.org/MPL/
- *
- * Software distributed under the License is distributed on an "AS IS" basis,
- * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
- * for the specific language governing rights and limitations under the
- * License.
- *
- * The Original Code is the Mozilla SVG project.
- *
- * The Initial Developer of the Original Code is
- * Crocodile Clips Ltd..
- * Portions created by the Initial Developer are Copyright (C) 2002
- * the Initial Developer. All Rights Reserved.
- *
- * Contributor(s):
- *   Alex Fritze <alex.fritze@crocodile-clips.com> (original author)
- *   Jonathan Watt <jonathan.watt@strath.ac.uk>
- *
- * Alternatively, the contents of this file may be used under the terms of
- * either of the GNU General Public License Version 2 or later (the "GPL"),
- * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
- * in which case the provisions of the GPL or the LGPL are applicable instead
- * of those above. If you wish to allow use of your version of this file only
- * under the terms of either the GPL or the LGPL, and not to allow others to
- * use your version of this file under the terms of the MPL, indicate your
- * decision by deleting the provisions above and replace them with the notice
- * and other provisions required by the GPL or the LGPL. If you do not delete
- * the provisions above, a recipient may use your version of this file under
- * the terms of any one of the MPL, the GPL or the LGPL.
- *
- * ***** END LICENSE BLOCK ***** */
-
-#ifndef __NS_ISVGSVGELEMENT__
-#define __NS_ISVGSVGELEMENT__
-
-#include "nsISupports.h"
-#include "nsIDOMSVGSVGElement.h"
-
-class nsSVGSVGElement;
-class nsIDOMSVGNumber;
-class nsISVGEnum;
-
-////////////////////////////////////////////////////////////////////////
-// nsISVGSVGElement: private interface implemented by <svg>-elements
-
-#define NS_ISVGSVGELEMENT_IID \
-{ 0x65195064, 0x9a5f, 0x42df, { 0xa1, 0x1f, 0x4c, 0x05, 0xbc, 0xa4, 0xe7, 0x28 } }
-
-class nsISVGSVGElement : public nsIDOMSVGSVGElement
-{
-public:
-  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISVGSVGELEMENT_IID)
-
-  NS_IMETHOD GetCurrentScaleNumber(nsIDOMSVGNumber **aResult)=0;
-  NS_IMETHOD GetZoomAndPanEnum(nsISVGEnum **aResult)=0;
-
-  /**
-   * For use by zoom controls to allow currentScale, currentTranslate.x and
-   * currentTranslate.y to be set by a single operation that dispatches a
-   * single SVGZoom event (instead of one SVGZoom and two SVGScroll events).
-   */
-  NS_IMETHOD SetCurrentScaleTranslate(float s, float x, float y)=0;
-
-  /**
-   * For use by pan controls to allow currentTranslate.x and currentTranslate.y
-   * to be set by a single operation that dispatches a single SVGScroll event
-   * (instead of two).
-   */
-  NS_IMETHOD SetCurrentTranslate(float x, float y)=0;
-
-  /**
-   * Record the current values of currentScale, currentTranslate.x and
-   * currentTranslate.y prior to changing the value of one of them.
-   */
-  NS_IMETHOD_(void) RecordCurrentScaleTranslate()=0;
-
-  /**
-   * Retrieve the value of currentScale, currentTranslate.x or
-   * currentTranslate.y prior to the last change made to any one of them.
-   */
-  NS_IMETHOD_(float) GetPreviousScale()=0;
-  NS_IMETHOD_(float) GetPreviousTranslate_x()=0;
-  NS_IMETHOD_(float) GetPreviousTranslate_y()=0;
-};
-
-NS_DEFINE_STATIC_IID_ACCESSOR(nsISVGSVGElement, NS_ISVGSVGELEMENT_IID)
-
-#endif // __NS_ISVGSVGELEMENT__
diff --git a/mozilla/content/svg/content/src/nsSVGElement.cpp b/mozilla/content/svg/content/src/nsSVGElement.cpp
index d8bf9748bf5..d90920318d2 100644
--- a/mozilla/content/svg/content/src/nsSVGElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGElement.cpp
@@ -55,7 +55,6 @@
 #include "nsIXBLService.h"
 #include "nsGkAtoms.h"
 #include "nsICSSStyleRule.h"
-#include "nsISVGSVGElement.h"
 #include "nsRuleWalker.h"
 #include "nsCSSDeclaration.h"
 #include "nsCSSProps.h"
diff --git a/mozilla/content/svg/content/src/nsSVGFilterElement.cpp b/mozilla/content/svg/content/src/nsSVGFilterElement.cpp
index b04f846ca5c..4d9f89a25cc 100644
--- a/mozilla/content/svg/content/src/nsSVGFilterElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGFilterElement.cpp
@@ -37,7 +37,6 @@
 #include "nsGkAtoms.h"
 #include "nsSVGLength.h"
 #include "nsCOMPtr.h"
-#include "nsISVGSVGElement.h"
 #include "nsSVGAnimatedEnumeration.h"
 #include "nsSVGAnimatedInteger.h"
 #include "nsSVGAnimatedString.h"
diff --git a/mozilla/content/svg/content/src/nsSVGForeignObjectElement.cpp b/mozilla/content/svg/content/src/nsSVGForeignObjectElement.cpp
index b222d43eeef..b2c4b0b33b2 100644
--- a/mozilla/content/svg/content/src/nsSVGForeignObjectElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGForeignObjectElement.cpp
@@ -38,7 +38,6 @@
 
 #include "nsSVGLength.h"
 #include "nsCOMPtr.h"
-#include "nsISVGSVGElement.h"
 #include "nsSVGForeignObjectElement.h"
 
 nsSVGElement::LengthInfo nsSVGForeignObjectElement::sLengthInfo[4] =
diff --git a/mozilla/content/svg/content/src/nsSVGGradientElement.cpp b/mozilla/content/svg/content/src/nsSVGGradientElement.cpp
index cdf8f515f94..1d63da3656b 100644
--- a/mozilla/content/svg/content/src/nsSVGGradientElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGGradientElement.cpp
@@ -45,7 +45,6 @@
 #include "nsIDOMSVGGradientElement.h"
 #include "nsSVGAnimatedString.h"
 #include "nsCOMPtr.h"
-#include "nsISVGSVGElement.h"
 #include "nsSVGStylableElement.h"
 #include "nsGkAtoms.h"
 #include "nsSVGGradientElement.h"
diff --git a/mozilla/content/svg/content/src/nsSVGGraphicElement.cpp b/mozilla/content/svg/content/src/nsSVGGraphicElement.cpp
index 19809d3057b..ca02d988720 100644
--- a/mozilla/content/svg/content/src/nsSVGGraphicElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGGraphicElement.cpp
@@ -42,7 +42,6 @@
 #include "nsSVGAnimatedTransformList.h"
 #include "nsGkAtoms.h"
 #include "nsSVGMatrix.h"
-#include "nsISVGSVGElement.h"
 #include "nsIDOMEventTarget.h"
 #include "nsBindingManager.h"
 #include "nsIFrame.h"
diff --git a/mozilla/content/svg/content/src/nsSVGImageElement.cpp b/mozilla/content/svg/content/src/nsSVGImageElement.cpp
index dd54285311f..22a97e1937e 100644
--- a/mozilla/content/svg/content/src/nsSVGImageElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGImageElement.cpp
@@ -40,7 +40,6 @@
 #include "nsSVGLength.h"
 #include "nsSVGAnimatedString.h"
 #include "nsCOMPtr.h"
-#include "nsISVGSVGElement.h"
 #include "nsIURI.h"
 #include "nsNetUtil.h"
 #include "nsSVGAnimatedPreserveAspectRatio.h"
diff --git a/mozilla/content/svg/content/src/nsSVGMaskElement.cpp b/mozilla/content/svg/content/src/nsSVGMaskElement.cpp
index d1b4dd52bbe..68ec235ef00 100644
--- a/mozilla/content/svg/content/src/nsSVGMaskElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGMaskElement.cpp
@@ -38,7 +38,6 @@
 #include "nsSVGAnimatedEnumeration.h"
 #include "nsIDOMSVGAnimatedEnum.h"
 #include "nsCOMPtr.h"
-#include "nsISVGSVGElement.h"
 #include "nsGkAtoms.h"
 #include "nsSVGMaskElement.h"
 
diff --git a/mozilla/content/svg/content/src/nsSVGPatternElement.cpp b/mozilla/content/svg/content/src/nsSVGPatternElement.cpp
index c21661b71b2..c9b9ceea6c5 100644
--- a/mozilla/content/svg/content/src/nsSVGPatternElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGPatternElement.cpp
@@ -43,7 +43,6 @@
 #include "nsIDOMSVGAnimatedEnum.h"
 #include "nsSVGAnimatedString.h"
 #include "nsCOMPtr.h"
-#include "nsISVGSVGElement.h"
 #include "nsGkAtoms.h"
 #include "nsSVGAnimatedRect.h"
 #include "nsSVGRect.h"
diff --git a/mozilla/content/svg/content/src/nsSVGSVGElement.cpp b/mozilla/content/svg/content/src/nsSVGSVGElement.cpp
index 5ce09c6b663..abcdef47909 100644
--- a/mozilla/content/svg/content/src/nsSVGSVGElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGSVGElement.cpp
@@ -88,7 +88,6 @@ NS_INTERFACE_MAP_BEGIN(nsSVGSVGElement)
   NS_INTERFACE_MAP_ENTRY(nsIDOMSVGFitToViewBox)
   NS_INTERFACE_MAP_ENTRY(nsIDOMSVGLocatable)
   NS_INTERFACE_MAP_ENTRY(nsIDOMSVGZoomAndPan)
-  NS_INTERFACE_MAP_ENTRY(nsISVGSVGElement)
   NS_INTERFACE_MAP_ENTRY_CONTENT_CLASSINFO(SVGSVGElement)
 NS_INTERFACE_MAP_END_INHERITING(nsSVGSVGElementBase)
 
@@ -745,7 +744,7 @@ nsSVGSVGElement::GetCTM(nsIDOMSVGMatrix **_retval)
       break;
     }
 
-    nsSVGSVGElement *viewportElement = QI_TO_NSSVGSVGELEMENT(ancestor);
+    nsSVGSVGElement *viewportElement = QI_AND_CAST_TO_NSSVGSVGELEMENT(ancestor);
     if (viewportElement) {
       rv = viewportElement->GetViewboxToViewportTransform(getter_AddRefs(ancestorCTM));
       if (NS_FAILED(rv)) return rv;
@@ -980,7 +979,7 @@ nsSVGSVGElement::SetZoomAndPan(PRUint16 aZoomAndPan)
 }
 
 //----------------------------------------------------------------------
-// nsISVGSVGElement methods:
+// helper methods for implementing SVGZoomEvent:
 
 NS_IMETHODIMP
 nsSVGSVGElement::GetCurrentScaleNumber(nsIDOMSVGNumber **aResult)
diff --git a/mozilla/content/svg/content/src/nsSVGSVGElement.h b/mozilla/content/svg/content/src/nsSVGSVGElement.h
index fd7686cd983..734644f8b13 100644
--- a/mozilla/content/svg/content/src/nsSVGSVGElement.h
+++ b/mozilla/content/svg/content/src/nsSVGSVGElement.h
@@ -41,22 +41,23 @@
 #define __NS_SVGSVGELEMENT_H__
 
 #include "nsSVGStylableElement.h"
-#include "nsISVGSVGElement.h"
+#include "nsIDOMSVGSVGElement.h"
 #include "nsIDOMSVGFitToViewBox.h"
 #include "nsIDOMSVGLocatable.h"
 #include "nsIDOMSVGZoomAndPan.h"
 #include "nsIDOMSVGMatrix.h"
 #include "nsSVGLength2.h"
 
-#define QI_TO_NSSVGSVGELEMENT(base)                                           \
-  NS_STATIC_CAST(nsSVGSVGElement*,                                            \
-    NS_STATIC_CAST(nsISVGSVGElement*,                                         \
-      nsCOMPtr<nsISVGSVGElement>(do_QueryInterface(base))));
+class nsISVGEnum;
+
+#define QI_AND_CAST_TO_NSSVGSVGELEMENT(base)                                  \
+  (nsCOMPtr<nsIDOMSVGSVGElement>(do_QueryInterface(base)) ?                   \
+   NS_STATIC_CAST(nsSVGSVGElement*, base.get()) : nsnull)
 
 typedef nsSVGStylableElement nsSVGSVGElementBase;
 
 class nsSVGSVGElement : public nsSVGSVGElementBase,
-                        public nsISVGSVGElement, // : nsIDOMSVGSVGElement
+                        public nsIDOMSVGSVGElement,
                         public nsIDOMSVGFitToViewBox,
                         public nsIDOMSVGLocatable,
                         public nsIDOMSVGZoomAndPan
@@ -75,7 +76,6 @@ protected:
   void SetCoordCtxRect(nsIDOMSVGRect* aCtxRect);
 
 public:
-  NS_DECLARE_STATIC_IID_ACCESSOR(NS_ISVGSVGELEMENT_IID)
 
   // interfaces:
   NS_DECL_ISUPPORTS_INHERITED
@@ -89,12 +89,34 @@ public:
   NS_FORWARD_NSIDOMELEMENT(nsSVGSVGElementBase::)
   NS_FORWARD_NSIDOMSVGELEMENT(nsSVGSVGElementBase::)
 
-  // nsISVGSVGElement interface:
+  // helper methods for implementing SVGZoomEvent:
   NS_IMETHOD GetCurrentScaleNumber(nsIDOMSVGNumber **aResult);
   NS_IMETHOD GetZoomAndPanEnum(nsISVGEnum **aResult);
+
+  /**
+   * For use by zoom controls to allow currentScale, currentTranslate.x and
+   * currentTranslate.y to be set by a single operation that dispatches a
+   * single SVGZoom event (instead of one SVGZoom and two SVGScroll events).
+   */
   NS_IMETHOD SetCurrentScaleTranslate(float s, float x, float y);
+
+  /**
+   * For use by pan controls to allow currentTranslate.x and currentTranslate.y
+   * to be set by a single operation that dispatches a single SVGScroll event
+   * (instead of two).
+   */
   NS_IMETHOD SetCurrentTranslate(float x, float y);
+
+  /**
+   * Record the current values of currentScale, currentTranslate.x and
+   * currentTranslate.y prior to changing the value of one of them.
+   */
   NS_IMETHOD_(void) RecordCurrentScaleTranslate();
+
+  /**
+   * Retrieve the value of currentScale, currentTranslate.x or
+   * currentTranslate.y prior to the last change made to any one of them.
+   */
   NS_IMETHOD_(float) GetPreviousTranslate_x();
   NS_IMETHOD_(float) GetPreviousTranslate_y();
   NS_IMETHOD_(float) GetPreviousScale();
diff --git a/mozilla/content/svg/content/src/nsSVGTSpanElement.cpp b/mozilla/content/svg/content/src/nsSVGTSpanElement.cpp
index bf61f251686..d3495e68800 100644
--- a/mozilla/content/svg/content/src/nsSVGTSpanElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGTSpanElement.cpp
@@ -42,7 +42,6 @@
 #include "nsCOMPtr.h"
 #include "nsSVGAnimatedLengthList.h"
 #include "nsSVGLengthList.h"
-#include "nsISVGSVGElement.h"
 #include "nsSVGSVGElement.h"
 #include "nsISVGTextContentMetrics.h"
 #include "nsIFrame.h"
diff --git a/mozilla/content/svg/content/src/nsSVGTextElement.cpp b/mozilla/content/svg/content/src/nsSVGTextElement.cpp
index 668c70db2d0..ca1217a1e49 100644
--- a/mozilla/content/svg/content/src/nsSVGTextElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGTextElement.cpp
@@ -42,7 +42,6 @@
 #include "nsCOMPtr.h"
 #include "nsSVGAnimatedLengthList.h"
 #include "nsSVGLengthList.h"
-#include "nsISVGSVGElement.h"
 #include "nsSVGSVGElement.h"
 #include "nsISVGTextContentMetrics.h"
 #include "nsIFrame.h"
diff --git a/mozilla/content/svg/content/src/nsSVGUseElement.cpp b/mozilla/content/svg/content/src/nsSVGUseElement.cpp
index fb3aaff032f..bdc14f8f14e 100644
--- a/mozilla/content/svg/content/src/nsSVGUseElement.cpp
+++ b/mozilla/content/svg/content/src/nsSVGUseElement.cpp
@@ -38,7 +38,6 @@
 #include "nsIDOMSVGGElement.h"
 #include "nsGkAtoms.h"
 #include "nsIDOMSVGAnimatedLength.h"
-#include "nsISVGSVGElement.h"
 #include "nsIDOMSVGAnimatedString.h"
 #include "nsSVGAnimatedString.h"
 #include "nsIDOMDocument.h"
diff --git a/mozilla/layout/svg/base/src/nsSVGOuterSVGFrame.cpp b/mozilla/layout/svg/base/src/nsSVGOuterSVGFrame.cpp
index e364f2e76dc..23731c12f75 100644
--- a/mozilla/layout/svg/base/src/nsSVGOuterSVGFrame.cpp
+++ b/mozilla/layout/svg/base/src/nsSVGOuterSVGFrame.cpp
@@ -137,9 +137,7 @@ NS_NewSVGOuterSVGFrame(nsIPresShell* aPresShell, nsIContent* aContent, nsStyleCo
 {  
   nsCOMPtr<nsIDOMSVGSVGElement> svgElement = do_QueryInterface(aContent);
   if (!svgElement) {
-#ifdef DEBUG
-    printf("warning: trying to construct an SVGOuterSVGFrame for a content element that doesn't support the right interfaces\n");
-#endif
+    NS_ERROR("Can't create frame! Content is not an SVG 'svg' element!");
     return nsnull;
   }
 
@@ -157,13 +155,11 @@ nsSVGOuterSVGFrame::nsSVGOuterSVGFrame(nsStyleContext* aContext)
 NS_IMETHODIMP
 nsSVGOuterSVGFrame::InitSVG()
 {
-  nsCOMPtr<nsISVGSVGElement> SVGElement = do_QueryInterface(mContent);
-  NS_ASSERTION(SVGElement, "wrong content element");
-
   nsIDocument* doc = mContent->GetCurrentDoc();
   if (doc) {
     // we only care about our content's zoom and pan values if it's the root element
     if (doc->GetRootContent() == mContent) {
+      nsSVGSVGElement *SVGElement = NS_STATIC_CAST(nsSVGSVGElement*, mContent);
       SVGElement->GetZoomAndPanEnum(getter_AddRefs(mZoomAndPan));
       SVGElement->GetCurrentTranslate(getter_AddRefs(mCurrentTranslate));
       SVGElement->GetCurrentScaleNumber(getter_AddRefs(mCurrentScale));