Extract invoke-main stub generator.

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

Index: pkg/compiler/lib/src/js_emitter/program_builder.dart
diff --git a/pkg/compiler/lib/src/js_emitter/program_builder.dart b/pkg/compiler/lib/src/js_emitter/program_builder.dart
index a6d6fe80549fcc46ced09404fc74937ac082a22c..f2200589c2fab42c1370d93d03d37880026af7ec 100644
--- a/pkg/compiler/lib/src/js_emitter/program_builder.dart
+++ b/pkg/compiler/lib/src/js_emitter/program_builder.dart
@@ -19,6 +19,7 @@ import 'js_emitter.dart' show
     ClassStubGenerator,
     CodeEmitterTask,
     InterceptorStubGenerator,
+    MainCallStubGenerator,
     ParameterStubGenerator,
     TypeTestGenerator,
     TypeTestProperties;
@@ -152,7 +153,7 @@ class ProgramBuilder {
     MainFragment result = new MainFragment(
         librariesMap.outputUnit,
         "",  // The empty string is the name for the main output file.
-        backend.emitter.staticFunctionAccess(_compiler.mainFunction),
+        _buildInvokeMain(),
         _buildLibraries(librariesMap),
         _buildStaticNonFinalFields(librariesMap),
         _buildStaticLazilyInitializedFields(librariesMap),
@@ -162,6 +163,12 @@ class ProgramBuilder {
     return result;
   }
 
+  js.Statement _buildInvokeMain() {
+    MainCallStubGenerator generator =
+        new MainCallStubGenerator(_compiler, backend, backend.emitter);
+    return generator.generateInvokeMain();
+  }
+
   DeferredFragment _buildDeferredOutput(MainFragment mainOutput,
                                       LibrariesMap librariesMap) {
     DeferredFragment result = new DeferredFragment(