Revert "Making all DOM types abstract and removing superfluous Dartium constructors."

tools/dom/scripts/htmldartgenerator.py

Index: tools/dom/scripts/htmldartgenerator.py
diff --git a/tools/dom/scripts/htmldartgenerator.py b/tools/dom/scripts/htmldartgenerator.py
index 4222f0f4e33ef542472f80a9e20ea5922648923f..b4bccf95575221b3f0cfc7f56a7bc7a926ca2a41 100644
--- a/tools/dom/scripts/htmldartgenerator.py
+++ b/tools/dom/scripts/htmldartgenerator.py
@@ -491,14 +491,7 @@ class HtmlDartGenerator(object):
         ORIGINAL_FUNCTION = html_name)
 
   def EmitHelpers(self, base_class):
-    if not self._members_emitter:
-      return
-
-    self._members_emitter.Emit(
-        '  // To suppress missing implicit constructor warnings.\n'
-        '  factory $CLASSNAME._() { '
-        'throw new UnsupportedError("Not supported"); }\n',
-        CLASSNAME=self._interface_type_info.implementation_name())
+    pass
 
   def DeclareAttribute(self, attribute, type_name, attr_name, read_only):
     """ Declares an attribute but does not include the code to invoke it.