Removed DARTIUM codegen for IDLS (sdk/lib/dartium)

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

 // Copyright (c) 2014, 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;
 
 @DocsEditable()
 $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$MIXINS$IMPLEMENTS {
 $!MEMBERS
 
     /// Checks if HTML imports are supported on the current platform.
   bool get supportsImport {
-$if DART2JS
     return JS('bool', '("import" in #)', this);
-$else
-    return true;
-$endif
   }
 }