Refined types for most HtmlElement factory constructors

sdk/lib/svg/dartium/svg_dartium.dart

 /**
  * Scalable Vector Graphics:
  * Two-dimensional vector graphics with support for events and animation.
  *
  * For details about the features and syntax of SVG, a W3C standard,
  * refer to the
  * [Scalable Vector Graphics Specification](http://www.w3.org/TR/SVG/).
  */
 library dart.dom.svg;
 
@@ skipping 6108 matching lines @@
 
   List<Element> get children => new FilteredElementList(this);
 
   set children(List<Element> value) {
     final children = this.children;
     children.clear();
     children.addAll(value);
   }
 
   String get outerHtml {
-    final container = new Element.tag("div");
+    final container = new DivElement();
     final SvgElement cloned = this.clone(true);
     container.children.add(cloned);
     return container.innerHtml;
   }
 
   String get innerHtml {
-    final container = new Element.tag("div");
+    final container = new DivElement();
     final SvgElement cloned = this.clone(true);
     container.children.addAll(cloned.children);
     return container.innerHtml;
   }
 
   set innerHtml(String value) {
     this.setInnerHtml(value);
   }
 
   DocumentFragment createFragment(String svg,
@@ skipping 1937 matching lines @@
    * Constructor instantiated by the DOM when a custom element has been created.
    *
    * This can only be called by subclasses from their created constructor.
    */
   _SVGMPathElement.created() : super.created();
 
   // Override these methods for Dartium _SVGMPathElement can't be abstract.
   AnimatedString get href => _blink.BlinkSVGMPathElement.instance.href_Getter_(this);
 }