Compute [WorldImpact] for main method as entrypoint

tests/compiler/dart2js/kernel/closed_world_test.dart

Index: tests/compiler/dart2js/kernel/closed_world_test.dart
diff --git a/tests/compiler/dart2js/kernel/closed_world_test.dart b/tests/compiler/dart2js/kernel/closed_world_test.dart
index 4d4630851cafe6bcf1f8c38927669c5b6db128f7..aa21341c486b6532ef270d32d4fc57b6ac76bc4f 100644
--- a/tests/compiler/dart2js/kernel/closed_world_test.dart
+++ b/tests/compiler/dart2js/kernel/closed_world_test.dart
@@ -44,7 +44,7 @@ class C implements B {
 class D implements C {
   D.a();
 }
-main() {
+main(args) {
   new A.a();
   new A.b();
   new C.a();
@@ -102,7 +102,12 @@ main(List<String> args) {
     backend.typeVariableHandler = new TypeVariableHandler(compiler);
 
     backend.enqueueHelpers(enqueuer);
-    enqueuer.addToWorkList(compiler.mainFunction);
+    enqueuer.applyImpact(
+        compiler.impactStrategy,
+        enqueuer.nativeEnqueuer
+            .processNativeClasses(compiler.libraryLoader.libraries));
+    enqueuer.applyImpact(compiler.impactStrategy,
+        backend.computeMainImpact(enqueuer, compiler.mainFunction));
     enqueuer.forEach((work) {
       AstElement element = work.element;
       ResolutionImpact resolutionImpact = build(compiler, element.resolvedAst);