Use entities in CommonElements interface.

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

 // Copyright (c) 2015, 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.js_helpers.impact;
 
 import '../common/names.dart';
 import '../compiler.dart' show Compiler;
 import '../core_types.dart' show CommonElements;
 import '../elements/resolution_types.dart' show ResolutionInterfaceType;
@@ skipping 158 matching lines @@
         staticUses: compiler.options.useKernel
             ? [
                 helpers.genericNoSuchMethod,
                 helpers.unresolvedConstructorError,
                 helpers.unresolvedStaticMethodError,
                 helpers.unresolvedStaticGetterError,
                 helpers.unresolvedStaticSetterError,
                 helpers.unresolvedTopLevelMethodError,
                 helpers.unresolvedTopLevelGetterError,
                 helpers.unresolvedTopLevelSetterError,
-                commonElements.symbolConstructor.declaration,
+                commonElements.symbolConstructor,
               ]
             : [
                 helpers.throwNoSuchMethod,
               ],
         otherImpacts: [
           // Also register the types of the arguments passed to this method.
           _needsList(
               'Needed to encode the arguments for throw NoSuchMethodError.'),
           _needsString('Needed to encode the name for throw NoSuchMethodError.')
         ]);
@@ skipping 98 matching lines @@
   BackendImpact get symbolConstructor {
     return _symbolConstructor ??=
         new BackendImpact(staticUses: [helpers.symbolValidatedConstructor]);
   }
 
   BackendImpact _constSymbol;
 
   BackendImpact get constSymbol {
     return _constSymbol ??= new BackendImpact(
         instantiatedClasses: [commonElements.symbolClass],
-        staticUses: [commonElements.symbolConstructor.declaration]);
+        staticUses: [commonElements.symbolConstructor]);
   }
 
   /// Helper for registering that `int` is needed.
   BackendImpact _needsInt(String reason) {
     // TODO(johnniwinther): Register [reason] for use in dump-info.
     return intValues;
   }
 
   /// Helper for registering that `List` is needed.
   BackendImpact _needsList(String reason) {
@@ skipping 420 matching lines @@
 
   BackendImpact _staticClosure;
 
   /// Backend impact for performing closurization of a top-level or static
   /// function.
   BackendImpact get staticClosure {
     return _staticClosure ??=
         new BackendImpact(globalClasses: [helpers.closureClass]);
   }
 }