Support SVGElement#elements, #innerHTML, and #outerHTML. Also add a .svg constructor.

client/html/src/SVGSVGElementWrappingImplementation.dart

 // Copyright (c) 2011, 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.
 
 class SVGSVGElementWrappingImplementation extends SVGElementWrappingImplementation implements SVGSVGElement {
   SVGSVGElementWrappingImplementation._wrap(ptr) : super._wrap(ptr) {}
 
   factory SVGSVGElementWrappingImplementation() {
     var el = new SVGElement.tag("svg");
     // The SVG spec requires the version attribute to match the spec version
-    el.attributes['version'] = 1.1;
+    el.attributes['version'] = "1.1";
     return el;
   }
 
   String get contentScriptType() { return _ptr.contentScriptType; }
 
   void set contentScriptType(String value) { _ptr.contentScriptType = value; }
 
   String get contentStyleType() { return _ptr.contentStyleType; }
 
   void set contentStyleType(String value) { _ptr.contentStyleType = value; }
@@ skipping 188 matching lines @@
   SVGAnimatedPreserveAspectRatio get preserveAspectRatio() { return LevelDom.wrapSVGAnimatedPreserveAspectRatio(_ptr.preserveAspectRatio); }
 
   SVGAnimatedRect get viewBox() { return LevelDom.wrapSVGAnimatedRect(_ptr.viewBox); }
 
   // From SVGZoomAndPan
 
   int get zoomAndPan() { return _ptr.zoomAndPan; }
 
   void set zoomAndPan(int value) { _ptr.zoomAndPan = value; }
 }