only focus webview after fields have been set

on some platforms the old approach was causing a focus+blur event to
fire with the old note contents

fixes

https://anki.tenderapp.com/discussions/beta-testing/681-red-cloze

and probably fixes

https://anki.tenderapp.com/discussions/beta-testing/683-back-input-returns

aqt/editor.py

@@ -264,10 +264,9 @@ class Editor:
                 return
             self.setupForegroundButton()
             self.checkValid()
-            runHook("loadNote", self)
-
             if focusTo is not None:
                 self.web.setFocus()
+            runHook("loadNote", self)
 
         self.web.evalWithCallback("setFields(%s, %s); setFonts(%s); focusField(%s)" % (
             json.dumps(data), json.dumps(self.prewrapMode()),