Make atob() throw an InvalidCharacterError on excess padding characters

Source/core/page/DOMWindow.cpp

 /*
  * Copyright (C) 2006, 2007, 2008, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 949 matching lines @@
 {
     if (encodedString.isNull())
         return String();
 
     if (!encodedString.containsOnlyLatin1()) {
         ec = InvalidCharacterError;
         return String();
     }
 
     Vector<char> out;
-    if (!base64Decode(encodedString, out, Base64FailOnInvalidCharacter)) {
+    if (!base64Decode(encodedString, out, Base64FailOnInvalidCharacter, Base64StrictPaddingValidation)) {
         ec = InvalidCharacterError;
         return String();
     }
 
     return String(out.data(), out.size());
 }
 
 bool DOMWindow::find(const String& string, bool caseSensitive, bool backwards, bool wrap, bool /*wholeWord*/, bool /*searchInFrames*/, bool /*showDialog*/) const
 {
     if (!isCurrentlyDisplayedInFrame())
@@ skipping 974 matching lines @@
 
     Frame* child = frame->tree()->scopedChild(index);
     if (child)
         return child->document()->domWindow();
 
     return 0;
 }
 
 
 } // namespace WebCore