Exposing native doubles as doubles when they are read-only or method return values.

tools/dom/scripts/htmldartgenerator.py

 #!/usr/bin/python
 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 """This module provides shared functionality for the system to generate
 dart:html APIs from the IDL database."""
 
 import emitter
 from generator import AnalyzeOperation, ConstantOutputOrder, \
@@ skipping 607 matching lines @@
         for attr in self._interface.attributes)
 
     template = self._template_loader.Load(
         template_file,
         {
           'DEFINE_LENGTH_AS_NUM_ITEMS': not has_length and has_num_items,
           'DEFINE_LENGTH_SETTER': not has_length_setter,
         })
     self._members_emitter.Emit(template, E=element_name)
 
-  def SecureOutputType(self, type_name, is_dart_type=False):
+  def SecureOutputType(self, type_name, is_dart_type=False,
+      can_narrow_type=False):
     """ Converts the type name to the secure type name for return types.
+    Arguments:
+      can_narrow_type - True if the output type can be narrowed further than
+        what would be accepted for input, used to narrow num APIs down to double
+        or int.
     """
     if is_dart_type:
       dart_name = type_name
     else:
-      dart_name = self._DartType(type_name)
+      type_info = self._TypeInfo(type_name)
+      dart_name = type_info.dart_type()
+      if can_narrow_type and dart_name == 'num':
+        dart_name = type_info.native_type()
+
     # We only need to secure Window.  Only local History and Location are
     # returned in generated code.
     assert(dart_name != 'HistoryBase' and dart_name != 'LocationBase')
     if dart_name == 'Window':
       return _secure_base_types[dart_name]
     return dart_name
 
   def SecureBaseName(self, type_name):
     if type_name in _secure_base_types:
       return _secure_base_types[type_name]
 
   def _DartType(self, type_name):
     return self._type_registry.DartType(type_name)
+
+  def _TypeInfo(self, type_name):
+    return self._type_registry.TypeInfo(type_name)