Merge CommonElements and BackendHelpers!

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

Index: pkg/compiler/lib/src/js_backend/type_variable_handler.dart
diff --git a/pkg/compiler/lib/src/js_backend/type_variable_handler.dart b/pkg/compiler/lib/src/js_backend/type_variable_handler.dart
index 996137d06c718aeb62d93b901c3a6ae9ebfcc1e4..bd2d38404d13c93a93906a5df80012daa541dc8f 100644
--- a/pkg/compiler/lib/src/js_backend/type_variable_handler.dart
+++ b/pkg/compiler/lib/src/js_backend/type_variable_handler.dart
@@ -15,7 +15,6 @@ import '../universe/use.dart' show ConstantUse;
 import '../universe/world_impact.dart';
 import 'backend.dart';
 import 'backend_usage.dart' show BackendUsageBuilder;
-import 'backend_helpers.dart';
 import 'backend_impact.dart';
 import 'mirrors_data.dart';
 
@@ -58,7 +57,7 @@ class TypeVariableResolutionAnalysis {
 /// Codegen handler that creates TypeVariable constants needed at runtime.
 class TypeVariableCodegenAnalysis {
   final JavaScriptBackend _backend;
-  final BackendHelpers _helpers;
+  final CommonElements _commonElements;
   final MirrorsData _mirrorsData;
 
   /**
@@ -79,7 +78,8 @@ class TypeVariableCodegenAnalysis {
   final StagedWorldImpactBuilder _impactBuilder =
       new StagedWorldImpactBuilder();
 
-  TypeVariableCodegenAnalysis(this._backend, this._helpers, this._mirrorsData);
+  TypeVariableCodegenAnalysis(
+      this._backend, this._commonElements, this._mirrorsData);
 
   CodeEmitterTask get _task => _backend.emitter;
   MetadataCollector get _metadataCollector => _task.metadataCollector;
@@ -109,10 +109,10 @@ class TypeVariableCodegenAnalysis {
           _metadataCollector.reifyType(typeVariableElement.bound);
       ConstantValue boundValue = new SyntheticConstantValue(
           SyntheticConstantKind.TYPEVARIABLE_REFERENCE, boundIndex);
-      ClassElement typeVariableClass = _helpers.typeVariableClass;
+      ClassElement typeVariableClass = _commonElements.typeVariableClass;
       ConstantExpression constant = new ConstructedConstantExpression(
           typeVariableClass.thisType,
-          _helpers.typeVariableConstructor,
+          _commonElements.typeVariableConstructor,
           const CallStructure.unnamed(3), [
         new TypeConstantExpression(cls.rawType, cls.name),
         new StringConstantExpression(currentTypeVariable.name),