fix text clipping cannot be removed from Frame

[Saumya-Mishra9129]

Fixes error given in cc5a070e767bb5559ecd058424d9b64c919ffdd3. @quozl @pro-panda @chimosky Please Review.

[chimosky]

Tested, thanks.

I get this traceback and issue still persists.

Traceback (most recent call last):
  File "/usr/lib/python3.7/dist-packages/jarabe/frame/clipboardmenu.py", line 173, in _remove_item_activate_cb
    cb_service.delete_object(self._cb_object.get_id())
  File "/usr/lib/python3.7/dist-packages/jarabe/frame/clipboard.py", line 104, in delete_object
    self.emit('object-deleted', object_id)
TypeError: could not convert type int to gint required for parameter 0
Traceback (most recent call last):
  File "/usr/lib/python3.7/dist-packages/jarabe/frame/clipboardmenu.py", line 173, in _remove_item_activate_cb
    cb_service.delete_object(self._cb_object.get_id())
  File "/usr/lib/python3.7/dist-packages/jarabe/frame/clipboard.py", line 99, in delete_object
    cb_object = self._objects.pop(object_id)
KeyError: 5851887540452339067

The file in the clipboard shows as bytes