dart2js: retain constants that are used as annotations in constructors and setters.

pkg/compiler/lib/src/js_emitter/code_emitter_task.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.js_emitter;
 
 const USE_NEW_EMITTER = const bool.fromEnvironment("dart2js.use.new.emitter");
 
 /**
  * Generates the code for all used classes in the program. Static fields (even
@@ skipping 178 matching lines @@
    */
   void computeNeededConstants() {
     // Make sure we retain all metadata of all elements. This could add new
     // constants to the handler.
     if (backend.mustRetainMetadata) {
       // TODO(floitsch): verify that we don't run through the same elements
       // multiple times.
       for (Element element in backend.generatedCode.keys) {
         if (backend.isAccessibleByReflection(element)) {
           bool shouldRetainMetadata = backend.retainMetadataOf(element);
-          if (shouldRetainMetadata && element.isFunction) {
+          if (shouldRetainMetadata &&
+              (element.isFunction || element.isConstructor ||
+               element.isSetter)) {
             FunctionElement function = element;
             function.functionSignature.forEachParameter(
                 backend.retainMetadataOf);
           }
         }
       }
       for (ClassElement cls in neededClasses) {
         final onlyForRti = typeTestRegistry.rtiNeededClasses.contains(cls);
         if (!onlyForRti) {
           backend.retainMetadataOf(cls);
@@ skipping 232 matching lines @@
   jsAst.Expression generateFunctionThatReturnsNull();
 
   int compareConstants(ConstantValue a, ConstantValue b);
   bool isConstantInlinedOrAlreadyEmitted(ConstantValue constant);
 
   /// Returns the JS code for accessing the given [constant].
   jsAst.Expression constantReference(ConstantValue constant);
 
   void invalidateCaches();
 }