Refined types for most HtmlElement factory constructors

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

Index: tools/dom/templates/html/impl/impl_SVGElement.darttemplate
diff --git a/tools/dom/templates/html/impl/impl_SVGElement.darttemplate b/tools/dom/templates/html/impl/impl_SVGElement.darttemplate
index fec3eb6a87d8615f8e9a705f41ef1cd3c442c979..886d783376fee336dd16049b44910c1ccdf9516c 100644
--- a/tools/dom/templates/html/impl/impl_SVGElement.darttemplate
+++ b/tools/dom/templates/html/impl/impl_SVGElement.darttemplate
@@ -65,14 +65,14 @@ $(ANNOTATIONS)$(NATIVESPEC)$(CLASS_MODIFIERS)class $CLASSNAME$EXTENDS$IMPLEMENTS
   }
 
   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;