Moved most of html lib generating scripts into tools.

tools/dom/templates/html/dart2js/impl_WorkerContext.darttemplate

 // Copyright (c) 2012, 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 html;
 
 /// @domName $DOMNAME
 class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 $!MEMBERS
 
   /**
    * Gets an instance of the Indexed DB factory to being using Indexed DB.
    *
    * Use [IdbFactory.supported] to check if Indexed DB is supported on the
    * current platform.
    */
   @SupportedBrowser(SupportedBrowser.CHROME, '23.0')
   @SupportedBrowser(SupportedBrowser.FIREFOX, '15.0')
   @SupportedBrowser(SupportedBrowser.IE, '10.0')
   @Experimental()
   IdbFactory get indexedDB =>
       JS('IdbFactory',
          '#.indexedDB || #.webkitIndexedDB || #.mozIndexedDB',
          this, this, this);
 }