IDL: Support nullable union types

Source/bindings/scripts/v8_types.py

Index: Source/bindings/scripts/v8_types.py
diff --git a/Source/bindings/scripts/v8_types.py b/Source/bindings/scripts/v8_types.py
index 944db4a604f6a029d45528807efeb4a48f8c9696..944fecef0eea2b7224a10122553a97e9c505e724 100644
--- a/Source/bindings/scripts/v8_types.py
+++ b/Source/bindings/scripts/v8_types.py
@@ -193,7 +193,7 @@ def cpp_type(idl_type, extended_attributes=None, raw_type=False, used_as_rvalue_
     if idl_type.is_dictionary:
         return base_idl_type
     if idl_type.is_union_type:
-        return idl_type.name
+        return idl_type.as_union_type.name
 
     # Default, assume native type is a pointer with same type name as idl type
     return base_idl_type + '*'
@@ -517,7 +517,7 @@ def v8_value_to_cpp_value(idl_type, extended_attributes, v8_value, variable_name
     # Simple types
     idl_type = idl_type.preprocessed_type
     add_includes_for_type(idl_type)
-    base_idl_type = idl_type.name if idl_type.is_union_type else idl_type.base_type
+    base_idl_type = idl_type.as_union_type.name if idl_type.is_union_type else idl_type.base_type
 
     if 'EnforceRange' in extended_attributes:
         arguments = ', '.join([v8_value, 'EnforceRange', 'exceptionState'])
@@ -862,7 +862,8 @@ def cpp_type_has_null_value(idl_type):
     #   a null pointer.
     # - 'Object' type. We use ScriptValue for object type.
     return (idl_type.is_string_type or idl_type.is_wrapper_type or
-            idl_type.is_enum or idl_type.base_type == 'object')
+            idl_type.is_enum or idl_type.is_union_type or
+            idl_type.base_type == 'object')
 
 IdlTypeBase.cpp_type_has_null_value = property(cpp_type_has_null_value)