Fixed element upgrading for polymer

tools/dom/templates/html/dartium/html_dartium.darttemplate

Index: tools/dom/templates/html/dartium/html_dartium.darttemplate
diff --git a/tools/dom/templates/html/dartium/html_dartium.darttemplate b/tools/dom/templates/html/dartium/html_dartium.darttemplate
index 3b70ccf173341d70f2c78d7bea59e26c7023eb76..25336a7e730db2f92f84b8e941f7189d3943a0de 100644
--- a/tools/dom/templates/html/dartium/html_dartium.darttemplate
+++ b/tools/dom/templates/html/dartium/html_dartium.darttemplate
@@ -351,6 +351,9 @@ Function _getSvgFunction(String key) {
  **********                                                          **********
  ******************************************************************************/
 
+// List of known tagName to DartClass for custom elements, used for upgrade.
+var _knownCustomeElements = new Map<String, Type>();
+
 Rectangle make_dart_rectangle(r) =>
     r == null ? null : new Rectangle(r['left'], r['top'], r['width'], r['height']);
 
@@ -420,11 +423,24 @@ wrap_jso(jsObject) {
       // Got a dart_class (it's a custom element) use it it's already set up.
       dartClass_instance = jsObject['dart_class'];
     } else {
-      var func = getHtmlCreateFunction(jsTypeName);
-      if (func != null) {
-        dartClass_instance = func();
-        dartClass_instance.blink_jsObject = jsObject;
-        js.setDartHtmlWrapperFor(jsObject, dartClass_instance);
+      var localName = jsObject['localName'];
+      var customElementClass = _knownCustomeElements[localName];
+      // Custom Element to upgrade.
+      if (jsTypeName == 'HTMLElement' && customElementClass != null) {
+        try {
+          dartClass_instance = _blink.Blink_Utils.constructElement(customElementClass, jsObject);
+        } finally {
+          dartClass_instance.blink_jsObject = jsObject;
+          jsObject['dart_class'] = dartClass_instance;
+          js.setDartHtmlWrapperFor(jsObject, dartClass_instance);
+       }
+      } else {
+        var func = getHtmlCreateFunction(jsTypeName);
+        if (func != null) {
+          dartClass_instance = func();
+          dartClass_instance.blink_jsObject = jsObject;
+          js.setDartHtmlWrapperFor(jsObject, dartClass_instance);
+        }
       }
     }
     return dartClass_instance;