Compute [WorldImpact] for main method as entrypoint

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

Index: pkg/compiler/lib/src/js_backend/backend.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend.dart b/pkg/compiler/lib/src/js_backend/backend.dart
index 3aca346a44573348d6c7619816716c32462852b8..4ef276bec241482cbca97de86b44cf150afbbe35 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -59,6 +59,7 @@ import '../universe/world_impact.dart'
         TransformedWorldImpact,
         WorldImpact,
         WorldImpactBuilder,
+        WorldImpactBuilderImpl,
         WorldImpactVisitor,
         StagedWorldImpactBuilder;
 import '../util/util.dart';
@@ -2577,12 +2578,26 @@ class JavaScriptBackend extends Backend {
     aliasedSuperMembers.remove(element);
   }
 
-  void registerMainHasArguments(Enqueuer enqueuer) {
-    // If the main method takes arguments, this compilation could be the target
-    // of Isolate.spawnUri. Strictly speaking, that can happen also if main
-    // takes no arguments, but in this case the spawned isolate can't
-    // communicate with the spawning isolate.
-    enqueuer.enableIsolateSupport();
+  @override
+  WorldImpact computeMainImpact(Enqueuer enqueuer, MethodElement mainMethod) {
+    WorldImpactBuilderImpl mainImpact = new WorldImpactBuilderImpl();
+    if (mainMethod.parameters.isNotEmpty) {
+      mainImpact.registerTypeUse(
+          new TypeUse.instantiation(backendClasses.listImplementation.rawType));
+      mainImpact.registerTypeUse(new TypeUse.instantiation(
+          backendClasses.stringImplementation.rawType));
+      mainImpact.registerStaticUse(
+          new StaticUse.staticInvoke(mainMethod, CallStructure.TWO_ARGS));
+
+      // If the main method takes arguments, this compilation could be the
+      // target of Isolate.spawnUri. Strictly speaking, that can happen also if
+      // main takes no arguments, but in this case the spawned isolate can't
+      // communicate with the spawning isolate.
+      enqueuer.enableIsolateSupport();
+    }
+    mainImpact.registerStaticUse(
+        new StaticUse.staticInvoke(mainMethod, CallStructure.NO_ARGS));
+    return mainImpact;
   }
 
   /// Returns the filename for the output-unit named [name].