Bug 664095 - Remove the override stylesheets when the editor is detached from the document as opposed to when it's destroyed for compatibility with the expected behavior from Composer; r=ehsan

editor/libeditor/html/nsHTMLEditor.cpp

@@ -168,11 +168,6 @@ nsHTMLEditor::~nsHTMLEditor()
   // free any default style propItems
   RemoveAllDefaultProperties();
 
-  while (mStyleSheetURLs.Length())
-  {
-    RemoveOverrideStyleSheet(mStyleSheetURLs[0]);
-  }
-
   if (mLinkHandler && mDocWeak)
   {
     nsCOMPtr<nsIPresShell> ps = GetPresShell();
@@ -359,6 +354,11 @@ nsHTMLEditor::PreDestroy(PRBool aDestroyingFrames)
     document->RemoveMutationObserver(this);
   }
 
+  while (mStyleSheetURLs.Length())
+  {
+    RemoveOverrideStyleSheet(mStyleSheetURLs[0]);
+  }
+
   return nsPlaintextEditor::PreDestroy(aDestroyingFrames);
 }