diff --git a/mozilla/content/html/document/src/nsHTMLDocument.cpp b/mozilla/content/html/document/src/nsHTMLDocument.cpp
index 97d8c4c5e17..6c45e6bfeed 100644
--- a/mozilla/content/html/document/src/nsHTMLDocument.cpp
+++ b/mozilla/content/html/document/src/nsHTMLDocument.cpp
@@ -3663,6 +3663,7 @@ nsHTMLDocument::CreateAndAddWyciwygChannel(void)
 
   // Note: we want to treat this like a "previous document" hint so that,
   // e.g. a <meta> tag in the document.write content can override it.
+  SetDocumentCharacterSetSource(kCharsetFromHintPrevDoc);
   mWyciwygChannel->SetCharsetAndSource(kCharsetFromHintPrevDoc,
                                        GetDocumentCharacterSet());
 
diff --git a/mozilla/dom/public/idl/base/nsIDOMWindowUtils.idl b/mozilla/dom/public/idl/base/nsIDOMWindowUtils.idl
index 18792cd4895..8eeeb06eec5 100644
--- a/mozilla/dom/public/idl/base/nsIDOMWindowUtils.idl
+++ b/mozilla/dom/public/idl/base/nsIDOMWindowUtils.idl
@@ -47,7 +47,7 @@
 
 interface nsIDOMElement;
 
-[scriptable, uuid(1F313394-73AB-41BF-8307-9FC5DA8A481E)]
+[scriptable, uuid(25f55fb2-a6f8-4f7f-93c3-3adafd5166bc)]
 interface nsIDOMWindowUtils : nsISupports {
 
   /**
@@ -69,6 +69,12 @@ interface nsIDOMWindowUtils : nsISupports {
    */
   attribute unsigned short imageAnimationMode;
 
+  /**
+   * Whether the charset of the window's current document has been forced by
+   * the user
+   */
+  readonly attribute boolean docCharsetIsForced;
+
   /**
    * Function to get metadata associated with the window's current document
    * @param aName the name of the metadata.  This should be all lowercase.
diff --git a/mozilla/dom/src/base/Makefile.in b/mozilla/dom/src/base/Makefile.in
index 329f353a7d9..17ffabe81ca 100644
--- a/mozilla/dom/src/base/Makefile.in
+++ b/mozilla/dom/src/base/Makefile.in
@@ -83,6 +83,7 @@ REQUIRES	= xpcom \
 		  xultmpl \
 		  jar \
 		  storage \
+		  htmlparser \
 		  $(NULL)
 
 ifdef NS_TRACE_MALLOC
diff --git a/mozilla/dom/src/base/nsDOMWindowUtils.cpp b/mozilla/dom/src/base/nsDOMWindowUtils.cpp
index 27959fd5ebf..0124bd1c644 100644
--- a/mozilla/dom/src/base/nsDOMWindowUtils.cpp
+++ b/mozilla/dom/src/base/nsDOMWindowUtils.cpp
@@ -52,6 +52,7 @@
 #include "nsIFrame.h"
 #include "nsIWidget.h"
 #include "nsGUIEvent.h"
+#include "nsIParser.h"
 
 #ifdef MOZ_ENABLE_GTK2
 #include <gdk/gdkx.h>
@@ -112,6 +113,23 @@ nsDOMWindowUtils::SetImageAnimationMode(PRUint16 aMode)
   return NS_ERROR_NOT_AVAILABLE;
 }
 
+NS_IMETHODIMP
+nsDOMWindowUtils::GetDocCharsetIsForced(PRBool *aIsForced)
+{
+  *aIsForced = PR_FALSE;
+
+  PRBool hasCap = PR_FALSE;
+  if (NS_FAILED(nsContentUtils::GetSecurityManager()->IsCapabilityEnabled("UniversalXPConnect", &hasCap)) || !hasCap)
+    return NS_ERROR_DOM_SECURITY_ERR;
+
+  if (mWindow) {
+    nsCOMPtr<nsIDocument> doc(do_QueryInterface(mWindow->GetExtantDocument()));
+    *aIsForced = doc &&
+      doc->GetDocumentCharacterSetSource() >= kCharsetFromParentForced;
+  }
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsDOMWindowUtils::GetDocumentMetadata(const nsAString& aName,
                                       nsAString& aValue)