Don't call dinvoke on Object methods

test/checker/checker_test.dart

 // Copyright (c) 2015, 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.
 
 /// General type checking tests
 library dev_compiler.test.checker_test;
 
 import 'package:unittest/unittest.dart';
 
 import 'package:dev_compiler/src/testing.dart';
 
 import '../test_util.dart';
 
 void main() {
   configureTest();
 
   test('conversion and dynamic invoke', () {
     testChecker({
+      '/helper.dart': '''
+      dynamic toString = (int x) => x + 42;
+      dynamic hashCode = "hello";
+      ''',
       '/main.dart': '''
+      import 'helper.dart' as helper;
+
       class A {
         String x = "hello world";
 
         void baz1(y) => x + y;
         static baz2(y) => y + y;
       }
 
       void foo(String str) {
         print(str);
       }
@@ skipping 21 matching lines @@
         (/*warning:DynamicInvoke*/f3("hello"));
         (/*warning:DynamicInvoke*/f3(42));
         StrFun f4 = foo;
         f4("hello");
         a.baz1("hello");
         var b1 = a.baz1;
         (/*warning:DynamicInvoke*/b1("hello"));
         A.baz2("hello");
         var b2 = A.baz2;
         (/*warning:DynamicInvoke*/b2("hello"));
+
+        dynamic a1 = new A();
+        (/*warning:DynamicInvoke*/a1.x);
+        a1.toString();
+        a1.hashCode;
+
+        dynamic toString = () => null;
+        (/*warning:DynamicInvoke*/toString());
+
+        (/*warning:DynamicInvoke*/helper.toString());
+        int hashCode = /*info:DynamicCast*/helper.hashCode;
     '''
     });
   });
 
   test('Primitives', () {
     testChecker({
       '/main.dart': '''
         int /*severe:InvalidVariableDeclaration*/a;
         double /*severe:InvalidVariableDeclaration*/b;
         num c;
@@ skipping 2729 matching lines @@
             f = bar as II2D;
             f = bar as DD2I;
             f = bar as DI2D;
             f = bar as ID2D;
             f = bar as DD2D;
           }
       '''
     });
   });
 }