IDL: Support nullable union types

Source/bindings/scripts/idl_types.py

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 """IDL type handling.
 
 Classes:
 IdlTypeBase
  IdlType
  IdlUnionType
  IdlArrayOrSequenceType
@@ skipping 256 matching lines @@
         }
 
     def __setstate__(self, state):
         self.member_types = state['member_types']
 
     @property
     def is_union_type(self):
         return True
 
     @property
+    def as_union_type(self):
+        # Note: Use this to "look through" a possible IdlNullableType wrapper.
+        return self
+
+    @property
     def name(self):
         """Return type name (or inner type name if nullable)
 
         http://heycam.github.io/webidl/#dfn-type-name
         """
         return 'Or'.join(member_type.name for member_type in self.member_types)
 
     def resolve_typedefs(self, typedefs):
         self.member_types = [
             typedefs.get(member_type, member_type)
@@ skipping 81 matching lines @@
     def is_nullable(self):
         return True
 
     @property
     def name(self):
         return self.inner_type.name + 'OrNull'
 
     def resolve_typedefs(self, typedefs):
         self.inner_type = self.inner_type.resolve_typedefs(typedefs)
         return self