Fix texImage2D on Dartium.

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

 // Copyright (c) 2013, 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 $CLASSNAME$EXTENDS$IMPLEMENTS$NATIVESPEC {
 $!MEMBERS
 
   /**
    * Sets the currently bound texture to [data].
    *
    * [data] can be either an [ImageElement], a
    * [CanvasElement], a [VideoElement], or an [ImageData] object.
    *
    * To use [texImage2d] with a TypedData object, use [texImage2dTyped].
    *
    */
   @DomName('WebGLRenderingContext.texImage2D')
 $if DART2JS
   @JSName('texImage2D')
   void texImage2D(int targetTexture, int levelOfDetail, int internalFormat,
       int format, int type, data) native;
 $else
   void texImage2D(int targetTexture, int levelOfDetail, int internalFormat,
       int format, int type, data) {
-    _texImage2D(targetTexture, levelOfDetail, internalFormat,
-        format, type, data);
+    if (data is ImageElement) {
+      texImage2DImage(targetTexture, levelOfDetail, internalFormat, format,
+          type, data);
+    } else if (data is ImageData) {
+      texImage2DImageData(targetTexture, levelOfDetail, internalFormat, format,
+          type, data);
+    } else if (data is CanvasElement) {
+      texImage2DCanvas(targetTexture, levelOfDetail, internalFormat, format,
+          type, data);
+    } else {
+      texImage2DVideo(targetTexture, levelOfDetail, internalFormat, format,
+          type, data);
+    }
   }
 $endif
 
   /**
    * Sets the currently bound texture to [data].
    */
 $if DART2JS
   @JSName('texImage2D')
   void texImage2DTyped(int targetTexture, int levelOfDetail,
       int internalFormat, int width, int height, int border, int format,
@@ skipping 38 matching lines @@
       int type, TypedData data) native;
 $else
   void texSubImage2DTyped(int targetTexture, int levelOfDetail,
       int internalFormat, int width, int height, int border, int format,
       int type, TypedData data) {
     _texSubImage2D(targetTexture, levelOfDetail, internalFormat,
         width, height, border, format, type, data);
   }
 $endif
 }