Move modules-dependent eventtarget code out of core.

Source/modules/modules.gypi

 {
   'variables': {
     # Experimental hooks for embedder to provide extra IDL and source files.
     #
     # Note: this is not a supported API. If you rely on this, you will be broken
     # from time to time as the code generator changes in backward incompatible
     # ways.
     'extra_blink_module_idl_files': [],
     'extra_blink_module_files': [],
     # Files for which bindings (.cpp and .h files) will be generated
@@ skipping 238 matching lines @@
       'serviceworkers/InstallPhaseEvent.idl',
       'speech/SpeechRecognitionError.idl',
       'speech/SpeechRecognitionEvent.idl',
       'speech/SpeechSynthesisEvent.idl',
       'webaudio/AudioProcessingEvent.idl',
       'webaudio/OfflineAudioCompletionEvent.idl',
       'webmidi/MIDIConnectionEvent.idl',
       'webmidi/MIDIMessageEvent.idl',
       'websockets/CloseEvent.idl',
     ],
+    'generated_modules_files': [
+      # .cpp files from make_modules_generated actions.
+      '<(SHARED_INTERMEDIATE_DIR)/blink/EventTargetModulesHeaders.h',
+      '<(SHARED_INTERMEDIATE_DIR)/blink/EventTargetModulesInterfaces.h',
+      '<(SHARED_INTERMEDIATE_DIR)/blink/EventTargetModulesNames.cpp',
+      '<(SHARED_INTERMEDIATE_DIR)/blink/EventTargetModulesNames.h',
+    ],
     'modules_files': [
       '<@(extra_blink_module_files)',
+      '<@(generated_modules_files)',
+      'InitModules.cpp',
+      'InitModules.h',
       'battery/BatteryDispatcher.cpp',
       'battery/BatteryDispatcher.h',
       'battery/BatteryManager.cpp',
       'battery/BatteryManager.h',
       'battery/BatteryStatus.cpp',
       'battery/BatteryStatus.h',
       'battery/NavigatorBattery.cpp',
       'battery/NavigatorBattery.h',
       'beacon/NavigatorBeacon.cpp',
       'beacon/NavigatorBeacon.h',
@@ skipping 656 matching lines @@
       'indexeddb/IDBKeyPathTest.cpp',
       'indexeddb/IDBRequestTest.cpp',
       'indexeddb/IDBTransactionTest.cpp',
       'websockets/WebSocketDeflaterTest.cpp',
       'websockets/WebSocketExtensionDispatcherTest.cpp',
       'websockets/WebSocketExtensionParserTest.cpp',
       'websockets/WebSocketPerMessageDeflateTest.cpp',
     ],
   },
 }