CanvasRenderingContext2D.fillText now works correctly with null maxWidth.

tools/dom/templates/html/impl/impl_CanvasRenderingContext2D.darttemplate

 // 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.
 
 part of $LIBRARYNAME;
 
 $(ANNOTATIONS)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 $!MEMBERS
 
   /**
@@ skipping 247 matching lines @@
       '#.lineDashOffset || #.webkitLineDashOffset', this, this);
 
   @DomName('CanvasRenderingContext2D.lineDashOffset')
   void set lineDashOffset(num value) => JS('void',
       'typeof #.lineDashOffset != "undefined" ? #.lineDashOffset = # : '
       '#.webkitLineDashOffset = #', this, this, value, this, value);
 $else
   // TODO(amouravski): Add Dartium native methods for drawImage once we figure
   // out how to not break native bindings.
 $endif
+
+$if DART2JS
+  /**
+   * Draws text to the canvas.
+   *
+   * The text is drawn starting at coordinates ([x], [y]).
+   * If [maxWidth] is provided and the [text] is computed to be wider than
+   * [maxWidth], then the drawn text is scaled down horizontally to fit.
+   *
+   * The text uses the current [CanvasRenderingContext2D.font] property for font
+   * options, such as typeface and size, and the current
+   * [CanvasRenderingContext2D.fillStyle] for style options such as color.
+   * The current [CanvasRenderingContext2D.textAlign] and
+   * [CanvasRenderingContext2D.textBaseLine] properties are also applied to the
+   * drawn text.
+   */
+  @DomName('CanvasRenderingContext2D.fillText')
+  void fillText(String text, num x, num y, [num maxWidth]) {
+    if (maxWidth != null) {
+      JS('void', '#.fillText(#, #, #, #)', this, text, x, y, maxWidth);
+    } else {
+      JS('void', '#.fillText(#, #, #)', this, text, x, y);
+    }
+  }
+$endif
 }
-