Rewrite how we handle synthesized constructors in the compiler. This was motivated by issue https:/…

sdk/lib/_internal/compiler/implementation/enqueue.dart

 // 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 dart2js;
 
 class EnqueueTask extends CompilerTask {
   final ResolutionEnqueuer resolution;
   final CodegenEnqueuer codegen;
 
@@ skipping 87 matching lines @@
   bool isProcessed(Element member);
 
   /**
    * Documentation wanted -- johnniwinther
    *
    * Invariant: [element] must be a declaration element.
    */
   void addToWorkList(Element element) {
     assert(invariant(element, element.isDeclaration));
     if (element.isForeign(compiler)) return;
-
-    if (element.isForwardingConstructor) {
-      addToWorkList(element.targetConstructor);
-      return;
-    }
-
     internalAddToWorkList(element);
   }
 
   /**
    * Adds [element] to the work list if it has not already been processed.
    */
   void internalAddToWorkList(Element element);
 
   void registerInstantiatedType(InterfaceType type, TreeElements elements) {
     ClassElement cls = type.element;
@@ skipping 605 matching lines @@
     while(!queue.isEmpty) {
       // TODO(johnniwinther): Find an optimal process order for codegen.
       f(queue.removeLast());
     }
   }
 
   void _logSpecificSummary(log(message)) {
     log('Compiled ${generatedCode.length} methods.');
   }
 }