Add a couple useful SVG constructors.

client/html/src/SVGSVGElement.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.
 
-// WARNING: Do not edit - generated code.
+interface SVGSVGElement extends SVGElement, SVGTests, SVGLangSpace, SVGExternalResourcesRequired, SVGStylable, SVGLocatable, SVGFitToViewBox, SVGZoomAndPan
+    factory SVGSVGElementWrappingImplementation {
 
-interface SVGSVGElement extends SVGElement, SVGTests, SVGLangSpace, SVGExternalResourcesRequired, SVGStylable, SVGLocatable, SVGFitToViewBox, SVGZoomAndPan {
+  SVGSVGElement();
 
   String get contentScriptType();
 
   void set contentScriptType(String value);
 
   String get contentStyleType();
 
   void set contentStyleType(String value);
 
   num get currentScale();
@@ skipping 63 matching lines @@
   void setCurrentTime(num seconds);
 
   int suspendRedraw(int maxWaitMilliseconds);
 
   void unpauseAnimations();
 
   void unsuspendRedraw(int suspendHandleId);
 
   void unsuspendRedrawAll();
 }