Make super.foo= erroneous if they are not assignable.

tests/compiler/dart2js/resolver_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
 import 'dart:async';
 import "package:async_helper/async_helper.dart";
 import 'dart:collection';
 
 import "package:compiler/src/resolution/resolution.dart";
@@ skipping 1159 matching lines @@
   // Can't override instance methods
   checkWarningOn('''
       main() { new B().bar(); }
       class B {
         mname() {}
         bar() {
           mname = () => null;
         }
       }
       ''', [MessageKind.SETTER_NOT_FOUND]);
+  checkWarningOn('''
+      main() { new B().bar(); }
+      class B {
+        mname() {}
+        bar() {
+          this.mname = () => null;
+        }
+      }
+      ''', [MessageKind.SETTER_NOT_FOUND]);
 
   // Can't override super methods
   checkWarningOn('''
       main() { new B().bar(); }
       class A {
         mname() {}
       }
       class B extends A {
         bar() {
           super.mname = () => 6;
         }
       }
-      ''', [MessageKind.SETTER_NOT_FOUND]);
+      ''', [MessageKind.ASSIGNING_METHOD_IN_SUPER]);
 
   // But index operators should be OK
   checkWarningOn('''
       main() { new B().bar(); }
       class B {
         operator[]=(x, y) {}
         bar() {
           this[1] = 3; // This is OK
         }
       }
@@ skipping 37 matching lines @@
 
   // Detect assignments to final fields:
   checkWarningOn('''
       main() => new B().m();
       class B {
         final x = 1;
         m() { x = 2; }
       }
       ''', [MessageKind.SETTER_NOT_FOUND]);
 
+  // ... even if 'this' is explicit:
+  checkWarningOn('''
+      main() => new B().m();
+      class B {
+        final x = 1;
+        m() { this.x = 2; }
+      }
+      ''', [MessageKind.SETTER_NOT_FOUND]);
+
   // ... and in super class:
   checkWarningOn('''
       main() => new B().m();
       class A {
         final x = 1;
       }
       class B extends A {
         m() { super.x = 2; }
       }
-      ''', [MessageKind.SETTER_NOT_FOUND]);
+      ''', [MessageKind.SETTER_NOT_FOUND_IN_SUPER]);
 
   // But non-final fields are OK:
   checkWarningOn('''
       main() => new B().m();
       class A {
         int x = 1;
       }
       class B extends A {
         m() { super.x = 2; }
       }
       ''', []);
 }
 
 
 /// Helper to test that [script] produces all the given [warnings].
 checkWarningOn(String script, List<MessageKind> warnings) {
   Expect.isTrue(warnings.length >= 0 && warnings.length <= 2);
   asyncTest(() => compileScript(script).then((compiler) {
     Expect.equals(0, compiler.errors.length);
     Expect.equals(warnings.length, compiler.warnings.length);
     for (int i = 0; i < warnings.length; i++) {
       Expect.equals(warnings[i], compiler.warnings[i].message.kind);
     }
   }));
 }