dart2js: don't emit tear-off data if not needed.

pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart

Index: pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart b/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
index 6e37f27edaf5e9bce1be9c4199c4851c21c1f9f6..54a834fdf804159efe8d5ec6f20268f1e3707bf7 100644
--- a/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/new_emitter/model_emitter.dart
@@ -505,10 +505,10 @@ class ModelEmitter {
   ///
   /// [Method.code]
   /// [DartMethod.callName]
+  /// [InstanceMethod.aliasName]
   /// [DartMethod.tearOffName]
   /// [JavaScriptBackend.isInterceptedMethod]
   /// functionType
-  /// [InstanceMethod.aliasName]
   ///
   /// followed by
   ///
@@ -529,15 +529,15 @@ function parseFunctionDescriptor(proto, name, descriptor) {
       proto[descriptor[pos]] = stub;
       funs.push(stub);
     }
-    if (descriptor[2] != null) {
-      var isIntercepted = descriptor[3];
-      var reflectionInfo = descriptor[4];
-      proto[descriptor[2]] = 
+    if (descriptor[3] != null) {
+      var isIntercepted = descriptor[4];
+      var reflectionInfo = descriptor[5];
+      proto[descriptor[3]] =
           tearOff(funs, reflectionInfo, false, name, isIntercepted);
     }
     // Install the alias for super calls on the prototype chain.

[floitsch, 2015/02/09 12:41:41]

Move this code into right order.
First a check for desc[2]. Then for desc[3] and then starting at pos == 6.

[zarah, 2015/02/09 15:52:00]

Acknowledged.

-    if (descriptor[5] != null) {
-      proto[descriptor[5]] = descriptor[0];
+    if (descriptor[2] != null) {
+      proto[descriptor[2]] = descriptor[0];
     }
   } else {
     proto[name] = descriptor;
@@ -571,19 +571,24 @@ function parseFunctionDescriptor(proto, name, descriptor) {
       if (method.needsTearOff || method.aliasName != null) {
         /// See [parseFunctionDescriptorBoilerplate] for a full description of
         /// the format.
-        // [name, [function, callName, tearOffName, isIntercepted, functionType,
-        //     aliasName, stub1_name, stub1_callName, stub1_code, ...]
-        bool isIntercepted = backend.isInterceptedMethod(method.element);
+        // [name, [function, callName, aliasName, tearOffName, isIntercepted,
+        // functionType, stub1_name, stub1_callName, stub1_code, ...]
         var data = [method.code];
         data.add(js.string(method.callName));
-        data.add(js.string(method.tearOffName));
-        data.add(new js.LiteralBool(isIntercepted));
-        data.add(_generateFunctionType(method.type));
+
         if (method.aliasName != null) {
           data.add(js.string(method.aliasName));
         } else {
           data.add(new js.LiteralNull());
         }
+
+        if (method.needsTearOff) {

[floitsch, 2015/02/09 12:41:41]

You can only avoid adding these if there aren't any parameterStubs. Otherwise
your stubs are shifted and you miss some of them.

[zarah, 2015/02/09 15:52:00]

Acknowledged.

+          data.add(js.string(method.tearOffName));
+          bool isIntercepted = backend.isInterceptedMethod(method.element);
+          data.add(new js.LiteralBool(isIntercepted));
+          data.add(_generateFunctionType(method.type));
+        }
+
         data.addAll(method.parameterStubs.expand(makeNameCallNameCodeTriplet));
         return [js.string(method.name), new js.ArrayInitializer(data)];
       } else {