Only remove the view from the set of views that are being Mirror-drawn when you're actually done reflecting on it

The previous code would always remove the view on exit, even if it had not previously added it (default: case of the switch)

In simple cases, this didn't really matter, but if you caused the logger to be reinvoked on self in a loop, then you would end up removing the view before you were done looping over it, and eventually run out of stack space

Fixes rdar://19558026



Swift SVN r24737

stdlib/objc/AppKit/AppKit.swift

@@ -107,11 +107,11 @@ struct _NSViewMirror : MirrorType {
               _v.cacheDisplayInRect(bounds, toBitmapImageRep: b)
               result = .Some(.View(b))
           }
+          
+          _NSViewMirror._views.removeObject(_v)
         default: ()
       }
       
-      _NSViewMirror._views.removeObject(_v)
-      
       return result
       
   } }