IDL: Add build target for IDL dictionary impl generation in core

Source/bindings/core/v8/BUILD.gn

 # 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.
 
 import("//third_party/WebKit/Source/bindings/core/idl.gni")
 
 import("//third_party/WebKit/Source/bindings/core/v8/generated.gni")
 import("//third_party/WebKit/Source/bindings/scripts/scripts.gni")
 import("//third_party/WebKit/Source/core/core.gni")
 
 visibility = "//third_party/WebKit/Source/*"
 
 # bindings_core_v8_generated in core/v8/generated.gyp
 group("bindings_core_v8_generated") {
   deps = [
+    ":bindings_core_dictionary_impl_generated",
     ":bindings_core_v8_generated_aggregate",
     ":bindings_core_v8_generated_individual",
   ]
 }
 
 # bindings_core_generated_aggregate in Source/bindings/core/v8/generated.gyp
 aggregate_generated_bindings("bindings_core_v8_generated_aggregate") {
   sources = core_idl_files
   component_dir = "core"
   outputs = bindings_core_generated_aggregate_files
 }
 
 # bindings_core_v8_generated_individual in Source/bindings/core/v8/generated.gyp
 idl_compiler("bindings_core_v8_generated_individual") {
   sources = core_interface_idl_files
   output_dir = bindings_core_v8_output_dir
 }
+
+# bindings_core_dictionary_impl_generated in Source/bindings/core/v8/generated.gyp
+idl_dictionary("bindings_core_dictionary_impl_generated") {
+  # FIXME: Add 'core_dictionary_idl_files' to sources
+  # See comment on core/core.gypi
+  sources = core_testing_dictionary_idl_files
+  # FIXME: Add 'generated_core_dictionary_files' to outputs
+  # See comment on core/core.gypi
+  outputs = generated_core_testing_dictionary_files
+}