Rename rendering/render_*.dart to rendering/*.dart

sky/tests/raw/render_flex.dart

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 import '../resources/third_party/unittest/unittest.dart';
 import '../resources/unit.dart';
 import '../resources/display_list.dart';
 import 'dart:sky' as sky;
 import 'package:sky/framework/app.dart';
-import 'package:sky/framework/rendering/render_block.dart';
-import 'package:sky/framework/rendering/render_box.dart';
-import 'package:sky/framework/rendering/render_flex.dart';
+import 'package:sky/framework/rendering/block.dart';
+import 'package:sky/framework/rendering/box.dart';
+import 'package:sky/framework/rendering/flex.dart';
 
 class RenderSolidColor extends RenderDecoratedBox {
   final sky.Size desiredSize;
   final int backgroundColor;
 
   RenderSolidColor(int backgroundColor, { this.desiredSize: const sky.Size.infinite() })
       : backgroundColor = backgroundColor,
         super(decoration: new BoxDecoration(backgroundColor: backgroundColor)) {
   }
 
@@ skipping 65 matching lines @@
     flexRoot.add(decoratedRow);
     decoratedRow.parentData.flex = 3;
     app = new TestApp(root);
 
     expect(root.size.width, equals(sky.view.width));
     expect(root.size.height, equals(sky.view.height));
     expect(renderBlock.size.width, equals(sky.view.width - 20.0));
 
   });
 }