Unify null treatment.

lib/dom/scripts/generator.py

Index: lib/dom/scripts/generator.py
diff --git a/lib/dom/scripts/generator.py b/lib/dom/scripts/generator.py
index 73a283e630c1c956317d1c97fa5911962473431d..aadb69b6392a5277e1513abe27b29499bec5c2ba 100644
--- a/lib/dom/scripts/generator.py
+++ b/lib/dom/scripts/generator.py
@@ -485,20 +485,19 @@ class IDLTypeInfo(object):
 
   def emit_to_native(self, emitter, idl_node, accept_null, name, handle, interface_name):
     if 'Callback' in idl_node.ext_attrs:
+      function_name = 'create'
       if accept_null:
-        flag = 'DartUtilities::ConvertNullToDefaultValue'
-      else:
-        flag = 'DartUtilities::ConvertNone'
+        function_name += 'WithNullCheck'
       emitter.Emit(
         '\n'
-        '        RefPtr<$TYPE> $NAME = Dart$IDL_TYPE::create($HANDLE, $FLAG, exception);\n'
+        '        RefPtr<$TYPE> $NAME = Dart$IDL_TYPE::$FUNCTION_NAME($HANDLE, exception);\n'
         '        if (exception)\n'
         '            goto fail;\n',
         TYPE=self.native_type(),
         NAME=name,
+        FUNCTION_NAME=function_name,
         IDL_TYPE=self.idl_type(),
-        HANDLE=handle,
-        FLAG=flag)
+        HANDLE=handle)
       return name
 
     argument = name
@@ -647,13 +646,12 @@ class PrimitiveIDLTypeInfo(IDLTypeInfo):
     return []
 
   def to_dart_conversion(self, value, interface_name=None, attributes=None):
-    conversion_arguments = [value]
-    if attributes and 'TreatReturnedNullStringAs' in attributes:
-      conversion_arguments.append('DartUtilities::ConvertNullToDefaultValue')
     function_name = self._capitalized_native_type()
     function_name = function_name[0].lower() + function_name[1:]
     function_name = 'DartUtilities::%sToDart' % function_name
-    return '%s(%s)' % (function_name, ', '.join(conversion_arguments))
+    if attributes and 'TreatReturnedNullStringAs' in attributes:
+      function_name += 'WithNullCheck'
+    return '%s(%s)' % (function_name, value)
 
   def webcore_getter_name(self):
     return self._data.webcore_getter_name