Merge CommonElements and BackendHelpers!

pkg/compiler/lib/src/js_emitter/full_emitter/interceptor_emitter.dart

Index: pkg/compiler/lib/src/js_emitter/full_emitter/interceptor_emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/full_emitter/interceptor_emitter.dart b/pkg/compiler/lib/src/js_emitter/full_emitter/interceptor_emitter.dart
index 6351c7bbfb470b4cbe54d4174341e93996566cfc..07eb13c93f9afaa10cb3b5c8e24f7341f3fe2490 100644
--- a/pkg/compiler/lib/src/js_emitter/full_emitter/interceptor_emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/full_emitter/interceptor_emitter.dart
@@ -49,7 +49,8 @@ class InterceptorEmitter extends CodeEmitterHelper {
       Set<ClassEntity> classes =
           backend.oneShotInterceptorData.getSpecializedGetInterceptorsFor(name);
       parts.add(js.statement('#.# = #', [
-        namer.globalObjectForLibrary(backend.helpers.interceptorsLibrary),
+        namer
+            .globalObjectForLibrary(backend.commonElements.interceptorsLibrary),
         name,
         buildGetInterceptorMethod(name, classes)
       ]));
@@ -65,8 +66,8 @@ class InterceptorEmitter extends CodeEmitterHelper {
 
     InterceptorStubGenerator stubGenerator =
         new InterceptorStubGenerator(compiler, namer, backend, closedWorld);
-    String globalObject =
-        namer.globalObjectForLibrary(backend.helpers.interceptorsLibrary);
+    String globalObject = namer
+        .globalObjectForLibrary(backend.commonElements.interceptorsLibrary);
     for (jsAst.Name name in names) {
       jsAst.Expression function =
           stubGenerator.generateOneShotInterceptor(name);