Emit diagnostics for bad NSM 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 3559724bea44f8bc7922f4c0dd156e70dd7b85b9..9f01c25031c0b608ae7114c43d278b8c15be58d7 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -1115,6 +1115,11 @@ class JavaScriptBackend extends Backend {
     rti.computeClassesNeedingRti();
   }
 
+  onInferenceComplete() {
+    super.onInferenceComplete();
+    noSuchMethodRegistry.onInferenceComplete();
+  }
+
   void registerGetRuntimeTypeArgument(Registry registry) {
     enqueueInResolution(getGetRuntimeTypeArgument(), registry);
     enqueueInResolution(getGetTypeArgumentByIndex(), registry);
@@ -1216,7 +1221,7 @@ class JavaScriptBackend extends Backend {
     enqueueClass(compiler.enqueuer.resolution, compiler.stringClass, registry);
   }
 
-  void registerNoSuchMethod(Element noSuchMethod) {
+  void registerNoSuchMethod(FunctionElement noSuchMethod) {
     noSuchMethodRegistry.registerNoSuchMethod(noSuchMethod);
   }
 
@@ -1399,6 +1404,7 @@ class JavaScriptBackend extends Backend {
 
   int assembleProgram() {
     int programSize = emitter.assembleProgram();
+    noSuchMethodRegistry.emitDiagnostic();
     int totalMethodCount = generatedCode.length;
     if (totalMethodCount != preMirrorsMethodCount) {
       int mirrorCount = totalMethodCount - preMirrorsMethodCount;