IDL build: Split global constructors into core and modules

Source/bindings/modules/modules.gypi

 # 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.
 
 {
   'includes': [
-    '../bindings.gypi',  # FIXME: factor out bindings_modules http://crbug.com/358074
     'v8/generated.gypi',
   ],
 
   'variables': {
-    'bindings_modules_output_dir': '<(bindings_output_dir)/modules',
+    'bindings_modules_output_dir': '<(SHARED_INTERMEDIATE_DIR)/bindings/modules',
   },
 }