[DO NOT LAND] Demonstrate partial interface/ImplementedAs bug

Source/modules/modules.gypi

 {
   'includes': [
     '../core/core_generated.gypi',
     'modules_generated.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
@@ skipping 223 matching lines @@
       'websockets/CloseEvent.idl',
       'websockets/WebSocket.idl',
     ],
     # 'partial interface' or target (right side of) 'implements'
     'modules_dependency_idl_files': [
       'background_sync/ServiceWorkerGlobalScopeSync.idl',
       'background_sync/ServiceWorkerRegistrationSync.idl',
       'battery/NavigatorBattery.idl',
       'beacon/NavigatorBeacon.idl',
       'bluetooth/NavigatorBluetooth.idl',
+      'c/WorkerC.idl',
       'credentialmanager/NavigatorCredentials.idl',
       'crypto/WindowCrypto.idl',
       'crypto/WorkerGlobalScopeCrypto.idl',
       'device_light/WindowDeviceLight.idl',
       'device_orientation/WindowDeviceMotion.idl',
       'device_orientation/WindowDeviceOrientation.idl',
       'donottrack/NavigatorDoNotTrack.idl',
       'encryptedmedia/HTMLMediaElementEncryptedMedia.idl',
       'encryptedmedia/NavigatorRequestMediaKeySystemAccess.idl',
       'fetch/WindowFetch.idl',
@@ skipping 309 matching lines @@
       'beacon/NavigatorBeacon.h',
       'bluetooth/Bluetooth.h',
       'bluetooth/BluetoothDevice.cpp',
       'bluetooth/BluetoothDevice.h',
       'bluetooth/BluetoothDiscovery.cpp',
       'bluetooth/BluetoothDiscovery.h',
       'bluetooth/BluetoothError.cpp',
       'bluetooth/BluetoothError.h',
       'bluetooth/NavigatorBluetooth.cpp',
       'bluetooth/NavigatorBluetooth.h',
+      'c/GlobalC.h',
       'compositorworker/CompositorWorker.cpp',
       'compositorworker/CompositorWorker.h',
       'compositorworker/CompositorWorkerGlobalScope.cpp',
       'compositorworker/CompositorWorkerGlobalScope.h',
       'compositorworker/CompositorWorkerMessagingProxy.cpp',
       'compositorworker/CompositorWorkerMessagingProxy.h',
       'compositorworker/CompositorWorkerThread.cpp',
       'compositorworker/CompositorWorkerThread.h',
       'credentialmanager/Credential.cpp',
       'credentialmanager/Credential.h',
@@ skipping 794 matching lines @@
       'indexeddb/IDBKeyPathTest.cpp',
       'indexeddb/IDBRequestTest.cpp',
       'indexeddb/IDBTransactionTest.cpp',
       'serviceworkers/CacheTest.cpp',
       'serviceworkers/ServiceWorkerContainerTest.cpp',
       'websockets/DOMWebSocketTest.cpp',
       'websockets/DocumentWebSocketChannelTest.cpp',
     ],
   },
 }