Avoid adding constants for emission during resolution.

pkg/compiler/lib/src/js_backend/mirrors_analysis.dart

 // Copyright (c) 2016, 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.
 
 library dart2js.mirrors_handler;
 
 import '../common.dart';
 import '../common/resolution.dart';
 import '../compiler.dart';
 import '../constants/values.dart';
@@ skipping 108 matching lines @@
       // necessary, but the backend relies on them being resolved.
       enqueuer.applyImpact(
           _computeImpactForReflectiveStaticFields(_findStaticFieldTargets()));
     }
 
     if (_mirrorsData.mustPreserveNames) _reporter.log('Preserving names.');
 
     if (_mirrorsData.mustRetainMetadata) {
       _reporter.log('Retaining metadata.');
 
-      (_compiler.libraryLoader.libraries as Iterable<LibraryElement>)
-          .forEach(_mirrorsData.retainMetadataOfLibrary);
+      for (LibraryEntity library in _compiler.libraryLoader.libraries) {
+        _mirrorsData.retainMetadataOfLibrary(library,
+            addForEmission: !enqueuer.isResolutionQueue);
+      }
 
       if (!enqueuer.queueIsClosed) {
         /// Register the constant value of [metadata] as live in resolution.
         void registerMetadataConstant(MetadataAnnotation metadata) {
           ConstantValue constant =
               _constants.getConstantValueForMetadata(metadata);
           Dependency dependency =
               new Dependency(constant, metadata.annotatedElement);
           _metadataConstants.add(dependency);
           _impactBuilder.registerConstantUse(new ConstantUse.mirrors(constant));
@@ skipping 336 matching lines @@
 
 /// Records that [constant] is used by the element behind [registry].
 class Dependency {
   final ConstantValue constant;
   final Element annotatedElement;
 
   const Dependency(this.constant, this.annotatedElement);
 
   String toString() => '$annotatedElement:${constant.toStructuredText()}';
 }