Remove unneeded delayed super-inits.

These were only needed back when axes_enter_events were generated in the
LocationEvent constructor, but this is now done by a standard callback.

Author: anntzer

lib/matplotlib/backend_bases.py

@@ -1405,6 +1405,7 @@ def on_press(event):
 
     def __init__(self, name, canvas, x, y, button=None, key=None,
                  step=0, dblclick=False, guiEvent=None):
+        super().__init__(name, canvas, x, y, guiEvent=guiEvent)
         if button in MouseButton.__members__.values():
             button = MouseButton(button)
         if name == "scroll_event" and button is None:
@@ -1417,10 +1418,6 @@ def __init__(self, name, canvas, x, y, button=None, key=None,
         self.step = step
         self.dblclick = dblclick
 
-        # super-init is deferred to the end because it calls back on
-        # 'axes_enter_event', which requires a fully initialized event.
-        super().__init__(name, canvas, x, y, guiEvent=guiEvent)
-
     def _process(self):
         if self.name == "button_press_event":
             self.canvas._button = self.button
@@ -1521,9 +1518,8 @@ def on_key(event):
     """
 
     def __init__(self, name, canvas, key, x=0, y=0, guiEvent=None):
-        self.key = key
-        # super-init deferred to the end: callback errors if called before
         super().__init__(name, canvas, x, y, guiEvent=guiEvent)
+        self.key = key
 
     def _process(self):
         if self.name == "key_press_event":