Revert "Fixing up Navigator.getUserMedia."

tools/dom/templates/html/impl/impl_MediaStream.darttemplate

-// Copyright (c) 2013, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-part of $LIBRARYNAME;
-
-/// @domName $DOMNAME; @docsEditable true$ANNOTATIONS
-class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
-$!MEMBERS
-
-  /**
-   * Checks if the MediaStream APIs are supported on the current platform.
-   *
-   * See also:
-   *
-   * * [Navigator.getUserMedia]
-   */
-$if DART2JS
-  static bool get supported =>
-    JS('bool', '''!!(#.getUserMedia || #.webkitGetUserMedia ||
-        #.mozGetUserMedia || #.msGetUserMedia)''',
-        window.navigator,
-        window.navigator,
-        window.navigator,
-        window.navigator);
-$else
-  static bool get supported => true;
-$endif
-}