Make atob() / btoa() argument non optional

Source/core/core.gypi

 {
     'variables': {
         'deprecated_perl_core_idl_files': [
             'css/CSS.idl',
             'css/CSSCharsetRule.idl',
             'css/CSSFontFaceLoadEvent.idl',
             'css/CSSFontFaceRule.idl',
             'css/CSSHostRule.idl',
             'css/CSSImportRule.idl',
             'css/CSSMediaRule.idl',
@@ skipping 273 matching lines @@
             'page/PerformanceResourceTiming.idl',
             'page/PerformanceTiming.idl',
             'page/Screen.idl',
             'page/SecurityPolicy.idl',
             'page/Selection.idl',
             'page/SpeechInputEvent.idl',
             'page/SpeechInputResult.idl',
             'page/SpeechInputResultList.idl',
             'page/WebKitPoint.idl',
             'page/Window.idl',
+            'page/WindowBase64.idl',
             'page/WorkerNavigator.idl',
             'plugins/MimeType.idl',
             'plugins/MimeTypeArray.idl',
             'plugins/Plugin.idl',
             'plugins/PluginArray.idl',
             'storage/Storage.idl',
             'storage/StorageEvent.idl',
             'workers/DedicatedWorkerGlobalScope.idl',
             'workers/SharedWorker.idl',
             'workers/SharedWorkerGlobalScope.idl',
@@ skipping 3474 matching lines @@
                 'bison_exe': 'bison',
                 # We specify a preprocess so it happens locally and won't get
                 # distributed to goma.
                 # FIXME: /usr/bin/gcc won't exist on OSX forever. We want to
                 # use /usr/bin/clang once we require Xcode 4.x.
                 'preprocessor': '--preprocessor "/usr/bin/gcc -E -P -x c++"'
               }],
          ],
     }
 }