Android improvements:

runtime/embedders/openglui/common/gl.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.
 
 library android_extension;
 
 class CanvasElement {
   int _height;
   int _width;
 
@@ skipping 377 matching lines @@
   final int height;
   final int width;
   ImageData(this.height, this.width, this.data);
 }
 
 class TextMetrics {
   final num width;
   TextMetrics(this.width);
 }
 
+void shutdown() {
+  CanvasRenderingContext2D.next_handle = 0;
+}
+
 class CanvasRenderingContext2D extends CanvasRenderingContext {
   // TODO(gram): We need to support multiple contexts, for cached content
   // prerendered to an offscreen buffer. For this we will use handles, with
   // handle 0 being the physical display.
-  static int _next_handle = 0;
+  static int next_handle = 0;
   int _handle = 0;
   get handle => _handle;
 
   int _width, _height;
   set width(int w) { _width = C2DSetWidth(_handle, w); }
   get width => _width;
   set height(int h) { _height = C2DSetHeight(_handle, h); }
   get height => _height;
 
   CanvasRenderingContext2D(canvas, width, height) : super(canvas) {
     _width = width;
     _height = height;
-    C2DCreateNativeContext(_handle = _next_handle++, width, height);
+    C2DCreateNativeContext(_handle = next_handle++, width, height);
   }
 
   double _alpha = 1.0;
   set globalAlpha(num a) {
     _alpha = C2DSetGlobalAlpha(_handle, a.toDouble());
   }
   get globalAlpha => _alpha;
 
   // TODO(gram): make sure we support compound assignments like:
   // fillStyle = strokeStyle = "red"
@@ skipping 306 matching lines @@
                             num dirtyWidth, num dirtyHeight]) {
     throw new Exception('Unimplemented webkitGetImageDataHD');
   }
 
   // TODO(vsm): Kill.
   noSuchMethod(invocation) {
       throw new Exception('Unimplemented/unknown ${invocation.memberName}');
   }
 }