Generate needed classes for constant maps in metadata.

sdk/lib/_internal/compiler/implementation/js_backend/backend.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 js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
@@ skipping 708 matching lines @@
       }
       if (type.element == typeImplementation) {
         // If we use a type literal in a constant, the compile time
         // constant emitter will generate a call to the createRuntimeType
         // helper so we register a use of that.
         registry.registerStaticInvocation(getCreateRuntimeType());
       }
     }
   }
 
-  void registerMetadataConstant(Constant constant,
+  void registerMetadataConstant(MetadataAnnotation metadata,
                                 Element annotatedElement,
                                 Registry registry) {
     assert(registry.isForResolution);
+    Constant constant = constants.getConstantForMetadata(metadata);
     registerCompileTimeConstant(constant, registry);
     metadataConstants.add(new Dependency(constant, annotatedElement));
   }
 
   void registerInstantiatedClass(ClassElement cls,
                                  Enqueuer enqueuer,
                                  Registry registry) {
     if (!cls.typeVariables.isEmpty) {
       typeVariableHandler.registerClassWithTypeVariables(cls);
     }
@@ skipping 1620 matching lines @@
   }
 }
 
 /// Records that [constant] is used by the element behind [registry].
 class Dependency {
   final Constant constant;
   final Element annotatedElement;
 
   const Dependency(this.constant, this.annotatedElement);
 }