diff --git a/mozilla/content/base/src/nsDocument.cpp b/mozilla/content/base/src/nsDocument.cpp
index 346a0920f92..b72a214fd52 100644
--- a/mozilla/content/base/src/nsDocument.cpp
+++ b/mozilla/content/base/src/nsDocument.cpp
@@ -932,6 +932,7 @@ nsDocument::SetHeaderData(nsIAtom* aHeaderField, const nsAReadableString& aData)
     else {
       nsDocHeaderData* data = mHeaderData;
       nsDocHeaderData** lastPtr = &mHeaderData;
+      PRBool found = PR_FALSE;
       do {  // look for existing and replace
         if (data->mField == aHeaderField) {
           if (!aData.IsEmpty()) {
@@ -942,13 +943,13 @@ nsDocument::SetHeaderData(nsIAtom* aHeaderField, const nsAReadableString& aData)
             data->mNext = nsnull;
             delete data;
           }
-          return NS_OK;
+          found = PR_TRUE;
         }
         lastPtr = &(data->mNext);
         data = data->mNext;
-      } while (nsnull != data);
-      // didn't find, append
-      if (!aData.IsEmpty()) {
+      } while (data && !found);
+      if (!aData.IsEmpty() && !found) {
+        // didn't find, append
         *lastPtr = new nsDocHeaderData(aHeaderField, aData);
       }
     }
@@ -956,22 +957,20 @@ nsDocument::SetHeaderData(nsIAtom* aHeaderField, const nsAReadableString& aData)
       // switch alternate style sheets based on default
       nsAutoString type;
       nsAutoString title;
-      nsAutoString textHtml;
-      textHtml.Assign(NS_LITERAL_STRING("text/html"));
       PRInt32 index;
 
-      mCSSLoader->SetPreferredSheet(nsAutoString(aData));
+      mCSSLoader->SetPreferredSheet(aData);
 
       PRInt32 count = mStyleSheets.Count();
       for (index = 0; index < count; index++) {
         nsIStyleSheet* sheet = (nsIStyleSheet*)mStyleSheets.ElementAt(index);
         sheet->GetType(type);
-        if (!type.Equals(textHtml)) {
+        if (!type.Equals(NS_LITERAL_STRING("text/html"))) {
           sheet->GetTitle(title);
           if (!title.IsEmpty()) {  // if sheet has title
-            nsAutoString data(aData);
-            PRBool disabled = (aData.IsEmpty() || 
-                               !title.EqualsIgnoreCase(data));
+            PRBool disabled = (aData.IsEmpty() ||
+                               Compare(title, aData,
+                                       nsCaseInsensitiveStringComparator()) != 0);
             SetStyleSheetDisabledState(sheet, disabled);
           }
         }
diff --git a/mozilla/content/html/style/public/nsICSSLoader.h b/mozilla/content/html/style/public/nsICSSLoader.h
index 11e18cc4967..7fbbc53d559 100644
--- a/mozilla/content/html/style/public/nsICSSLoader.h
+++ b/mozilla/content/html/style/public/nsICSSLoader.h
@@ -24,6 +24,7 @@
 
 #include "nslayout.h"
 #include "nsISupports.h"
+#include "nsAReadableString.h"
 
 class nsIAtom;
 class nsString;
@@ -52,7 +53,7 @@ public:
 
   NS_IMETHOD SetCaseSensitive(PRBool aCaseSensitive) = 0;
   NS_IMETHOD SetQuirkMode(PRBool aQuirkMode) = 0;
-  NS_IMETHOD SetPreferredSheet(const nsString& aTitle) = 0;
+  NS_IMETHOD SetPreferredSheet(const nsAReadableString& aTitle) = 0;
 
   // Get/Recycle a CSS parser for general use
   NS_IMETHOD GetParserFor(nsICSSStyleSheet* aSheet,
diff --git a/mozilla/content/html/style/src/nsCSSLoader.cpp b/mozilla/content/html/style/src/nsCSSLoader.cpp
index 0352bdf11d9..6c5a292e271 100644
--- a/mozilla/content/html/style/src/nsCSSLoader.cpp
+++ b/mozilla/content/html/style/src/nsCSSLoader.cpp
@@ -215,7 +215,7 @@ public:
 
   NS_IMETHOD SetCaseSensitive(PRBool aCaseSensitive);
   NS_IMETHOD SetQuirkMode(PRBool aQuirkMode);
-  NS_IMETHOD SetPreferredSheet(const nsString& aTitle);
+  NS_IMETHOD SetPreferredSheet(const nsAReadableString& aTitle);
 
   NS_IMETHOD GetParserFor(nsICSSStyleSheet* aSheet,
                           nsICSSParser** aParser);
@@ -520,7 +520,7 @@ CSSLoaderImpl::SetQuirkMode(PRBool aQuirkMode)
 }
 
 NS_IMETHODIMP
-CSSLoaderImpl::SetPreferredSheet(const nsString& aTitle)
+CSSLoaderImpl::SetPreferredSheet(const nsAReadableString& aTitle)
 {
   mPreferredSheet = aTitle;
 
diff --git a/mozilla/layout/style/nsCSSLoader.cpp b/mozilla/layout/style/nsCSSLoader.cpp
index 0352bdf11d9..6c5a292e271 100644
--- a/mozilla/layout/style/nsCSSLoader.cpp
+++ b/mozilla/layout/style/nsCSSLoader.cpp
@@ -215,7 +215,7 @@ public:
 
   NS_IMETHOD SetCaseSensitive(PRBool aCaseSensitive);
   NS_IMETHOD SetQuirkMode(PRBool aQuirkMode);
-  NS_IMETHOD SetPreferredSheet(const nsString& aTitle);
+  NS_IMETHOD SetPreferredSheet(const nsAReadableString& aTitle);
 
   NS_IMETHOD GetParserFor(nsICSSStyleSheet* aSheet,
                           nsICSSParser** aParser);
@@ -520,7 +520,7 @@ CSSLoaderImpl::SetQuirkMode(PRBool aQuirkMode)
 }
 
 NS_IMETHODIMP
-CSSLoaderImpl::SetPreferredSheet(const nsString& aTitle)
+CSSLoaderImpl::SetPreferredSheet(const nsAReadableString& aTitle)
 {
   mPreferredSheet = aTitle;
 
diff --git a/mozilla/layout/style/nsICSSLoader.h b/mozilla/layout/style/nsICSSLoader.h
index 11e18cc4967..7fbbc53d559 100644
--- a/mozilla/layout/style/nsICSSLoader.h
+++ b/mozilla/layout/style/nsICSSLoader.h
@@ -24,6 +24,7 @@
 
 #include "nslayout.h"
 #include "nsISupports.h"
+#include "nsAReadableString.h"
 
 class nsIAtom;
 class nsString;
@@ -52,7 +53,7 @@ public:
 
   NS_IMETHOD SetCaseSensitive(PRBool aCaseSensitive) = 0;
   NS_IMETHOD SetQuirkMode(PRBool aQuirkMode) = 0;
-  NS_IMETHOD SetPreferredSheet(const nsString& aTitle) = 0;
+  NS_IMETHOD SetPreferredSheet(const nsAReadableString& aTitle) = 0;
 
   // Get/Recycle a CSS parser for general use
   NS_IMETHOD GetParserFor(nsICSSStyleSheet* aSheet,