Create Namer and Emitter on codegen start.

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

Index: pkg/compiler/lib/src/js_emitter/parameter_stub_generator.dart
diff --git a/pkg/compiler/lib/src/js_emitter/parameter_stub_generator.dart b/pkg/compiler/lib/src/js_emitter/parameter_stub_generator.dart
index c63527dd713107ef205b25169c0462e2b98f252d..ad7f2edd61abdf334f21fa814afae535467b85ae 100644
--- a/pkg/compiler/lib/src/js_emitter/parameter_stub_generator.dart
+++ b/pkg/compiler/lib/src/js_emitter/parameter_stub_generator.dart
@@ -10,8 +10,10 @@ class ParameterStubGenerator {
   final Namer namer;
   final Compiler compiler;
   final JavaScriptBackend backend;
+  final ClosedWorld closedWorld;
 
-  ParameterStubGenerator(this.compiler, this.namer, this.backend);
+  ParameterStubGenerator(
+      this.compiler, this.namer, this.backend, this.closedWorld);
 
   Emitter get emitter => backend.emitter.emitter;
   CodeEmitterTask get emitterTask => backend.emitter;
@@ -267,8 +269,7 @@ class ParameterStubGenerator {
     for (Selector selector in selectors.keys) {
       if (renamedCallSelectors.contains(selector)) continue;
       if (!selector.appliesUnnamed(member)) continue;
-      if (!selectors[selector]
-          .applies(member, selector, compiler.closedWorld)) {
+      if (!selectors[selector].applies(member, selector, closedWorld)) {
         continue;
       }