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

Source/core/core.gypi

Index: Source/core/core.gypi
diff --git a/Source/core/core.gypi b/Source/core/core.gypi
index 2d6c4807ca5a6ff7bf5f6942424c90eb5399e888..0bbcd37a096ece093783e792f9883643c49312ef 100644
--- a/Source/core/core.gypi
+++ b/Source/core/core.gypi
@@ -488,6 +488,9 @@
             'workers/AbstractWorker.idl',
             'xml/DocumentXPathEvaluator.idl',
         ],
+        'core_idl_dictionary_files': [
+            'css/FontFaceDescriptors.idl',

[bashi, 2014/07/30 11:32:26]

It seems we need to write dictionary files twice(here and each generated.gypi
files)...

[haraken, 2014/07/30 19:57:36]

Can we probably define core_idl_dictionary_files in core.gypi, and add:

'includes': [
  'core/core.gypi'
]

to the gyp file that wants to use core_idl_dictionary_files? By including
core.gypi, you can use variables defined in the gypi file.

Nit: core_idl_dictionary_files => core_dictionary_idl_files (for consistency
with other xxx_idl_files)

[bashi, 2014/07/31 02:34:05]

The problem was that the relative paths can be different among this file and
other gyp files so I thought I can't share them. Anyway, I'll try different
approach.
Will do.

+        ],
         # interfaces that inherit from Event, including Event itself
         'core_event_idl_files': [
             'css/CSSFontFaceLoadEvent.idl',