Add FontFaceDescriptors IDL dictionary

Source/core/core.gypi

 {
     'includes': [
       'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/Animation.idl',
             'animation/AnimationEffect.idl',
             'animation/AnimationPlayer.idl',
@@ skipping 3314 matching lines @@
             'svg/graphics/SVGImageForContainer.h',
             'svg/graphics/filters/SVGFEImage.cpp',
             'svg/graphics/filters/SVGFEImage.h',
             'svg/graphics/filters/SVGFilter.cpp',
             'svg/graphics/filters/SVGFilter.h',
             'svg/graphics/filters/SVGFilterBuilder.cpp',
             'svg/graphics/filters/SVGFilterBuilder.h',
             'svg/properties/SVGAnimatedProperty.cpp',
             'svg/properties/SVGPropertyTearOff.cpp',
         ],
-        # FIXME: http://crbug.com/403150
-        # Add 'core_dictionary_idl_files' and
-        # 'generated_core_dictionary_files' variables.
-        # The variables should contain IDL dictionary files and generated files
-        # They would look like below:
-        # 'core_dictionary_idl_files': [
-        #   'css/FontFaceDescriptors.idl',
-        # ],
-        # 'generated_core_dictionary_files': [
-        #   '<(blink_core_output_dir)/css/FontFaceDescriptors.cpp',
-        #   '<(blink_core_output_dir)/css/FontFaceDescriptors.h',
-        # ],
+        'core_dictionary_idl_files': [
+          'css/FontFaceDescriptors.idl',
+        ],
+        'generated_core_dictionary_files': [
+          '<(blink_core_output_dir)/css/FontFaceDescriptors.cpp',
+          '<(blink_core_output_dir)/css/FontFaceDescriptors.h',
+        ],
         'core_testing_dictionary_idl_files': [
           'testing/InternalDictionary.idl',
         ],
         'webcore_testing_idl_files': [
           'testing/DictionaryTest.idl',
           'testing/GarbageCollectedScriptWrappable.idl',
           'testing/GCObservation.idl',
           'testing/InternalProfilers.idl',
           'testing/InternalSettings.idl',
           'testing/Internals.idl',
@@ skipping 142 matching lines @@
             'rendering/shapes/BoxShapeTest.cpp',
             'rendering/style/OutlineValueTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }