Fix mocking native classes and add a regression test.

pkg/dev_compiler/lib/src/compiler/code_generator.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.
 
 import 'dart:collection' show HashMap, HashSet;
 import 'dart:math' show min, max;
 
 import 'package:analyzer/analyzer.dart' hide ConstantEvaluator;
 import 'package:analyzer/dart/ast/ast.dart';
@@ skipping 1445 matching lines @@
     // abstract members. For example:
     //
     //     class C { m(); noSuchMethod(...) { ... } }
     //     class D extends C { m(); noSuchMethod(...) { ... } }
     //
     // We'll generate D.m even though it is not necessary.
     //
     // Doing better is a bit tricky, as our current codegen strategy for the
     // mock methods encodes information about the number of arguments (and type
     // arguments) that D expects.
-    return _collectMockMethods(type).map(_implementMockMethod);
+    return _collectMockMethods(type)
+        .map((method) => _implementMockMethod(method, type));
   }
 
   /// Given a class C that implements method M from interface I, but does not
   /// declare M, this will generate an implementation that forwards to
   /// noSuchMethod.
   ///
   /// For example:
   ///
   ///     class Cat {
   ///       bool eatFood(String food) => true;
   ///     }
   ///     class MockCat implements Cat {
   ///        noSuchMethod(Invocation invocation) => 3;
   ///     }
   ///
   /// It will generate an `eatFood` that looks like:
   ///
   ///     eatFood(...args) {
   ///       return core.bool.as(this.noSuchMethod(
   ///           new dart.InvocationImpl('eatFood', args)));
   ///     }
-  JS.Method _implementMockMethod(ExecutableElement method) {
+  JS.Method _implementMockMethod(ExecutableElement method, InterfaceType type) {
     var invocationProps = <JS.Property>[];
     addProperty(String name, JS.Expression value) {
       invocationProps.add(new JS.Property(js.string(name), value));
     }
 
     var args = new JS.TemporaryId('args');
     var fnArgs = <JS.Parameter>[];
     JS.Expression positionalArgs;
 
     if (method.type.namedParameterTypes.isNotEmpty) {
@@ skipping 30 matching lines @@
       fnBody = js.call('#._check(#)', [_emitType(method.returnType), fnBody]);
     }
 
     var fn = new JS.Fun(fnArgs, js.statement('{ return #; }', [fnBody]),
         typeParams: _emitTypeFormals(method.type.typeFormals));
 
     // TODO(jmesserly): generic type arguments will get dropped.
     // We have a similar issue with `dgsend` helpers.
     return new JS.Method(
         _declareMemberName(method,
-            useExtension:
-                _extensionTypes.isNativeClass(method.enclosingElement)),
+            useExtension: _extensionTypes.isNativeClass(type.element)),
         _makeGenericFunction(fn),
         isGetter: method is PropertyAccessorElement && method.isGetter,
         isSetter: method is PropertyAccessorElement && method.isSetter,
         isStatic: false);
   }
 
   /// Return `true` if the given [classElement] has a noSuchMethod() method
   /// distinct from the one declared in class Object, as per the Dart Language
   /// Specification (section 10.4).
   // TODO(jmesserly): this was taken from error_verifier.dart
@@ skipping 4339 matching lines @@
   if (targetIdentifier.staticElement is! PrefixElement) return false;
   var prefix = targetIdentifier.staticElement as PrefixElement;
 
   // The library the prefix is referring to must come from a deferred import.
   var containingLibrary = resolutionMap
       .elementDeclaredByCompilationUnit(target.root as CompilationUnit)
       .library;
   var imports = containingLibrary.getImportsWithPrefix(prefix);
   return imports.length == 1 && imports[0].isDeferred;
 }