Move remaining helpers to BackendHelpers

pkg/compiler/lib/src/js_emitter/main_call_stub_generator.dart

 // Copyright (c) 2014, 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;
 
 class MainCallStubGenerator {
   final Compiler compiler;
   final JavaScriptBackend backend;
   final CodeEmitterTask emitterTask;
 
   MainCallStubGenerator(this.compiler, this.backend, this.emitterTask);
 
+  BackendHelpers get helpers => backend.helpers;
+
   /// Returns the code equivalent to:
   ///   `function(args) { $.startRootIsolate(X.main$closure(), args); }`
   jsAst.Expression _buildIsolateSetupClosure(Element appMain,
                                              Element isolateMain) {
     jsAst.Expression mainAccess =
         emitterTask.isolateStaticClosureAccess(appMain);
     // Since we pass the closurized version of the main method to
     // the isolate method, we must make sure that it exists.
     return js('function(a){ #(#, a); }',
         [emitterTask.staticFunctionAccess(isolateMain), mainAccess]);
   }
 
-
   jsAst.Statement generateInvokeMain() {
     Element main = compiler.mainFunction;
     jsAst.Expression mainCallClosure = null;
     if (compiler.hasIsolateSupport) {
       Element isolateMain =
-        backend.isolateHelperLibrary.find(JavaScriptBackend.START_ROOT_ISOLATE);
+        helpers.isolateHelperLibrary.find(BackendHelpers.START_ROOT_ISOLATE);
       mainCallClosure = _buildIsolateSetupClosure(main, isolateMain);
     } else if (compiler.hasIncrementalSupport) {
       mainCallClosure = js(
           'function() { return #(); }',
           emitterTask.staticFunctionAccess(main));
     } else {
       mainCallClosure = emitterTask.staticFunctionAccess(main);
     }
 
     jsAst.Expression currentScriptAccess =
@@ skipping 32 matching lines @@
         if (typeof dartMainRunner === "function") {
           dartMainRunner(#mainCallClosure, []);
         } else {
           #mainCallClosure([]);
         }
       })''',
       {'currentScript': currentScriptAccess,
        'mainCallClosure': mainCallClosure});
   }
 }