dart2js: Add a pointer from the emitter's JS code to the encoding part.

pkg/compiler/lib/src/js_emitter/old_emitter/emitter.dart

 // 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 dart2js.js_emitter;
 
 
 class OldEmitter implements Emitter {
   final Compiler compiler;
   final CodeEmitterTask task;
@@ skipping 509 matching lines @@
            *   'Super;field1,field2'
            * from the CLASS_DESCRIPTOR_PROPERTY property on the descriptor.
            */
           var classData = desc["${namer.classDescriptorProperty}"],
               supr, fields = classData;
           if (#hasRetainedMetadata)
             if (typeof classData == "object" &&
                 classData instanceof Array) {
               classData = fields = classData[0];
             }
+          // ${ClassBuilder.fieldEncodingDescription}.
           var s = fields.split(";");
           fields = s[1] == "" ? [] : s[1].split(",");
           supr = s[0];
+          // ${ClassBuilder.functionTypeEncodingDescription}.
           split = supr.split(":");
           if (split.length == 2) {
             supr = split[0];
             var functionSignature = split[1];
             if (functionSignature)
               desc.$signaturePropertyName = (function(s) {
                   return function(){ return #metadata[s]; };
                 })(functionSignature);
           }
 
@@ skipping 1739 matching lines @@
     for (Element element in compiler.enqueuer.codegen.newlyEnqueuedElements) {
       if (element.isInstanceMember) {
         cachedClassBuilders.remove(element.enclosingClass);
 
         nativeEmitter.cachedBuilders.remove(element.enclosingClass);
 
       }
     }
   }
 }