Let EventTarget be a base class in the frog dom.

client/dom/scripts/dartgenerator.py

Index: client/dom/scripts/dartgenerator.py
diff --git a/client/dom/scripts/dartgenerator.py b/client/dom/scripts/dartgenerator.py
index f3fa63207b600b50ac7f276529dcd29e2260722f..1170444b0eca3ee6dd0dd1f2f822db9a3515c7ca 100755
--- a/client/dom/scripts/dartgenerator.py
+++ b/client/dom/scripts/dartgenerator.py
@@ -1988,24 +1988,9 @@ class FrogInterfaceGenerator(object):
     base = None
     if interface.parents:
       supertype = interface.parents[0].type.id
-      # FIXME: We're currently injecting List<..> and EventTarget as
-      # supertypes in dart.idl. We should annotate/preserve as
-      # attributes instead.  For now, this hack lets the interfaces
-      # inherit, but not the classes.
-      if (not _IsDartListType(supertype) and
-          not supertype == 'EventTarget'):
-        base = self._ImplClassName(supertype)
       if _IsDartCollectionType(supertype):
         # List methods are injected in AddIndexer.
         pass
-      elif supertype == 'EventTarget':
-        # Most implementors of EventTarget specify the EventListener operations
-        # again.  If the operations are not specified, try to inherit from the
-        # EventTarget implementation.
-        #
-        # Applies to MessagePort.
-        if not [op for op in interface.operations if op.id == 'addEventListener']:
-          base = self._ImplClassName(supertype)
       else:
         base = self._ImplClassName(supertype)