MNT : fix __init__ order in AnchoredSizeLocator

Trying to set the axes property before calling up the mro to the base
class (eventually Artist) `__init__` which means that the `_axes`
attribute is not yet attached to the instance object.

 - removed setting of `self.axes`, this is taken care of in the
   baseclass
 - moved rest of sub-class specific attributes to after call up mro
   stack

Author: tacaswell

lib/mpl_toolkits/axes_grid1/inset_locator.py

@@ -58,20 +58,21 @@ def __call__(self, ax, renderer):
 
         return bb
 
+
 from . import axes_size as Size
 
 
 class AnchoredSizeLocator(AnchoredLocatorBase):
     def __init__(self, bbox_to_anchor, x_size, y_size, loc,
                  borderpad=0.5, bbox_transform=None):
-        self.axes = None
-        self.x_size = Size.from_any(x_size)
-        self.y_size = Size.from_any(y_size)
 
         super(AnchoredSizeLocator, self).__init__(bbox_to_anchor, None, loc,
                                                  borderpad=borderpad,
                                                  bbox_transform=bbox_transform)
 
+        self.x_size = Size.from_any(x_size)
+        self.y_size = Size.from_any(y_size)
+
     def get_extent(self, renderer):
 
         x, y, w, h = self.get_bbox_to_anchor().bounds