message: Add one missing TS upgrade fix
diff: @@ -40,7 +40,7 @@ export class UnixPty implements Pty {
  private _onExitEventEmitter = new EventEmitter<void>();
  private _onAvailableWriteBufferSizeChangeEventEmitter = new EventEmitter<BufferSizeChange>();
  private _outstandingWriteDataCount = 0;
  - private _emitBufferSizeLater: (() => void) & _.Cancelable = null;
  + private _emitBufferSizeLater: _.DebouncedFunc<any> = null;
  // Amount of data which went directly to the OS but still needs to 'announced' via an event.
  private _directWrittenDataCount = 0;
  