fix #603, support mock objects

test/codegen_expected/language/no_such_method_subtype_test.js

 dart_library.library('language/no_such_method_subtype_test', null, /* Imports */[
   'dart_sdk',
   'expect'
 ], function load__no_such_method_subtype_test(exports, dart_sdk, expect) {
   'use strict';
   const core = dart_sdk.core;
   const _interceptors = dart_sdk._interceptors;
   const dart = dart_sdk.dart;
   const dartx = dart_sdk.dartx;
   const expect$ = expect.expect;
   const no_such_method_subtype_test = Object.create(null);
   let JSArrayOfA = () => (JSArrayOfA = dart.constFn(_interceptors.JSArray$(no_such_method_subtype_test.A)))();
   let VoidTodynamic = () => (VoidTodynamic = dart.constFn(dart.definiteFunctionType(dart.dynamic, [])))();
   no_such_method_subtype_test.A = class A extends core.Object {
     foo() {
       return 42;
     }
   };
   dart.setSignature(no_such_method_subtype_test.A, {
     methods: () => ({foo: dart.definiteFunctionType(dart.dynamic, [])})
   });
   no_such_method_subtype_test.B = class B extends core.Object {
     noSuchMethod(im) {
       return 84;
     }
+    foo() {
+      return this.noSuchMethod(new dart.InvocationImpl('foo', [], {isMethod: true}));
+    }
   };
   no_such_method_subtype_test.B[dart.implements] = () => [no_such_method_subtype_test.A];
   no_such_method_subtype_test.main = function() {
     let a = JSArrayOfA().of([new no_such_method_subtype_test.A(), new no_such_method_subtype_test.B()]);
     let b = a[dartx.get](1);
     if (no_such_method_subtype_test.A.is(b)) {
       expect$.Expect.equals(84, b.foo());
       return;
     }
     expect$.Expect.fail('Should not be here');
   };
   dart.fn(no_such_method_subtype_test.main, VoidTodynamic());
   // Exports:
   exports.no_such_method_subtype_test = no_such_method_subtype_test;
 });