Don't generate forwarding hooks if all noSuchMethod implementations

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 1ed077da32f754dbdefa76b2a66c7b3bbd76fb52..f4d001a9ff413161d7f0f0b7a0fb596c6516e8d8 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -577,6 +577,9 @@ class JavaScriptBackend extends Backend {
   /// constructors for custom elements.
   CustomElementsAnalysis customElementsAnalysis;
 
+  /// Support for classifying `noSuchMethod` implementations.
+  NoSuchMethodRegistry noSuchMethodRegistry;
+
   JavaScriptConstantTask constantCompilerTask;
 
   JavaScriptResolutionCallbacks resolutionCallbacks;
@@ -585,6 +588,8 @@ class JavaScriptBackend extends Backend {
 
   bool get canHandleCompilationFailed => true;
 
+  bool enabledNoSuchMethod = false;
+
   JavaScriptBackend(Compiler compiler, bool generateSourceMap)
       : namer = determineNamer(compiler),
         oneShotInterceptors = new Map<String, Selector>(),
@@ -595,6 +600,7 @@ class JavaScriptBackend extends Backend {
     emitter = new CodeEmitterTask(compiler, namer, generateSourceMap);
     typeVariableHandler = new TypeVariableHandler(this);
     customElementsAnalysis = new CustomElementsAnalysis(this);
+    noSuchMethodRegistry = new NoSuchMethodRegistry(this);
     constantCompilerTask = new JavaScriptConstantTask(compiler);
     resolutionCallbacks = new JavaScriptResolutionCallbacks(this);
     patchResolverTask = new PatchResolverTask(compiler);
@@ -1198,11 +1204,13 @@ class JavaScriptBackend extends Backend {
     enqueueClass(compiler.enqueuer.resolution, compiler.stringClass, registry);
   }
 
-  void enableNoSuchMethod(Element context, Enqueuer world) {
+  void registerNoSuchMethod(Element noSuchMethod) {
+    noSuchMethodRegistry.registerNoSuchMethod(noSuchMethod);
+  }
+
+  void enableNoSuchMethod(Enqueuer world) {
     enqueue(world, getCreateInvocationMirror(), compiler.globalDependencies);
     world.registerInvocation(compiler.noSuchMethodSelector);
-    // TODO(tyoverby): Send the context element to DumpInfoTask to be
-    // blamed.
   }
 
   void enableIsolateSupport(Enqueuer enqueuer) {
@@ -2391,6 +2399,14 @@ class JavaScriptBackend extends Backend {
     customElementsAnalysis.onQueueEmpty(enqueuer);
     if (!enqueuer.queueIsEmpty) return false;
 
+    noSuchMethodRegistry.onQueueEmpty();
+    if (!enabledNoSuchMethod &&
+        (noSuchMethodRegistry.hasThrowingNoSuchMethod ||
+         noSuchMethodRegistry.hasComplexNoSuchMethod)) {
+      enableNoSuchMethod(enqueuer);
+      enabledNoSuchMethod = true;
+    }
+
     if (compiler.hasIncrementalSupport) {
       // Always enable tear-off closures during incremental compilation.
       Element e = findHelper('closureFromTearOff');