Rename context2d to context2D.

samples/spirodraw/web/spirodraw.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 spirodraw;
 
 import 'dart:html';
 import 'dart:math' as Math;
 
 part "colorpicker.dart";
@@ skipping 32 matching lines @@
   Spirodraw() {
     doc = window.document;
     inOrOut = doc.query("#in_out");
     fixedRadiusSlider = doc.query("#fixed_radius");
     wheelRadiusSlider = doc.query("#wheel_radius");
     penRadiusSlider = doc.query("#pen_radius");
     penWidthSlider = doc.query("#pen_width");
     speedSlider = doc.query("#speed");
     mainDiv = doc.query("#main");
     frontCanvas = doc.query("#canvas");
-    front = frontCanvas.context2d;
+    front = frontCanvas.context2D;
     backCanvas = new Element.tag("canvas");
-    back = backCanvas.context2d;
+    back = backCanvas.context2D;
     paletteElement = doc.query("#palette");
     window.onResize.listen(onResize);
     initControlPanel();
   }
 
   void go() {
     onResize(null);
   }
 
   void onResize(Event event) {
@@ skipping 226 matching lines @@
 int gcf(int n, int d) {
   if (n == d) return n;
   int max = Math.max(n, d);
 
   for (int i = max ~/ 2; i > 1; i--) {
     if ((n % i == 0) && (d % i == 0)) return i;
   }
 
   return 1;
 }