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

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 470 matching lines @@
             'page/WindowPagePopup.idl',
             'svg/SVGDocument.idl',
             'svg/SVGFilterPrimitiveStandardAttributes.idl',
             'svg/SVGFitToViewBox.idl',
             'svg/SVGTests.idl',
             'svg/SVGURIReference.idl',
             'svg/SVGZoomAndPan.idl',
             'workers/AbstractWorker.idl',
             'xml/DocumentXPathEvaluator.idl',
         ],
+        'core_dictionary_idl_files': [
+            'css/FontFaceDescriptors.idl',
+        ],
         # interfaces that inherit from Event, including Event itself
         'core_event_idl_files': [
             'css/CSSFontFaceLoadEvent.idl',
             'events/AnimationPlayerEvent.idl',
             'events/ApplicationCacheErrorEvent.idl',
             'events/AutocompleteErrorEvent.idl',
             'events/BeforeUnloadEvent.idl',
             'events/CompositionEvent.idl',
             'events/CustomEvent.idl',
             'events/ErrorEvent.idl',
@@ skipping 2813 matching lines @@
           'testing/LayerRectList.idl',
           'testing/MallocStatistics.idl',
           'testing/PrivateScriptTest.idl',
           'testing/RefCountedScriptWrappable.idl',
           'testing/TypeConversions.idl',
         ],
         'generated_webcore_testing_idl_files': [
           '<(blink_core_output_dir)/InternalRuntimeFlags.idl',
           '<(blink_core_output_dir)/InternalSettingsGenerated.idl',
         ],
+        'generated_core_dictionary_files': [
+          '<(blink_core_output_dir)/css/FontFaceDescriptors.cpp',
+          '<(blink_core_output_dir)/css/FontFaceDescriptors.h',
+        ],
         'webcore_testing_files': [
             '<(blink_core_output_dir)/InternalSettingsGenerated.cpp',
             '<(blink_core_output_dir)/InternalSettingsGenerated.h',
             'testing/DummyPageHolder.cpp',
             'testing/DummyPageHolder.h',
             'testing/GarbageCollectedScriptWrappable.cpp',
             'testing/GarbageCollectedScriptWrappable.h',
             'testing/GCObservation.cpp',
             'testing/GCObservation.h',
             'testing/InternalProfilers.cpp',
@@ skipping 107 matching lines @@
             'rendering/RenderTableRowTest.cpp',
             'rendering/shapes/BoxShapeTest.cpp',
             'testing/PrivateScriptTestTest.cpp',
             'streams/ReadableStreamTest.cpp',
             'testing/UnitTestHelpers.cpp',
             'testing/UnitTestHelpers.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }