Remove the Promises old implementation.

Source/bindings/bindings.gypi

 {
     'variables': {
         'bindings_v8_dir': 'v8',
         'blink_output_dir': '<(SHARED_INTERMEDIATE_DIR)/blink',
         'bindings_output_dir': '<(SHARED_INTERMEDIATE_DIR)/blink/bindings',
         'bindings_files': [
             'v8/ActiveDOMCallback.cpp',
             'v8/ActiveDOMCallback.h',
             'v8/ArrayValue.cpp',
             'v8/ArrayValue.h',
@@ skipping 189 matching lines @@
             'v8/custom/V8Int8ArrayCustom.h',
             'v8/custom/V8JavaScriptCallFrameCustom.cpp',
             'v8/custom/V8LocationCustom.cpp',
             'v8/custom/V8MessageChannelCustom.cpp',
             'v8/custom/V8MessageEventCustom.cpp',
             'v8/custom/V8MessagePortCustom.cpp',
             'v8/custom/V8MutationObserverCustom.cpp',
             'v8/custom/V8NodeCustom.cpp',
             'v8/custom/V8PerformanceEntryCustom.cpp',
             'v8/custom/V8PopStateEventCustom.cpp',
-            'v8/custom/V8PromiseCustom.cpp',
             'v8/custom/V8SQLResultSetRowListCustom.cpp',
             'v8/custom/V8SQLTransactionCustom.cpp',
             'v8/custom/V8SQLTransactionSyncCustom.cpp',
             'v8/custom/V8SVGElementCustom.cpp',
             'v8/custom/V8SVGPathSegCustom.cpp',
             'v8/custom/V8ServiceWorkerCustom.cpp',
             'v8/custom/V8StyleSheetCustom.cpp',
             'v8/custom/V8SubtleCryptoCustom.cpp',
             'v8/custom/V8TextCustom.cpp',
             'v8/custom/V8TextTrackCueCustom.cpp',
@@ skipping 82 matching lines @@
             # supports this use case (gyp turns all actions into ninja restat
             # rules).
             ['"<(GENERATOR)"=="ninja"', {
               'write_file_only_if_changed': '1',
             }, {
               'write_file_only_if_changed': '0',
             }],
         ],
     },
 }