ERP5Workflow: perf: cleanup of doActionFor

Before this fix, checking that the action was possible from the
current state was not done correctly (isActionSupported was not
used to set the transition).

Also avoid to check if transition is in getTransitionValueList:
it is useless (transition *is* on of the workflow or is None!)
and calls the expensive 'objectValues' method

product/ERP5Workflow/Document/Workflow.py

@@ -297,26 +297,24 @@ class Workflow(IdAsReferenceMixin("", "prefix"), XMLObject):
     Allows the user to request a workflow action.  This method
     must perform its own security checks.
     '''
-    sdef = self._getWorkflowStateOf(document, id_only=0)
+    state = self._getWorkflowStateOf(document, id_only=0)
     kw['comment'] = comment
-    if sdef is None:
+    if state is None:
       raise WorkflowException(_(u'Object is in an undefined state.'))
-    if self.isActionSupported(document, action, **kw):
-      wf_id = self.getId()
-      if wf_id is None:
-        raise WorkflowException(
-            _(u'Requested workflow not found.'))
-    tdef = self._getOb(id=action)
-
-    if tdef not in self.getTransitionValueList():
+
+    if not self.isActionSupported(document, action, state=state, **kw):
+      # action is not allowed from the current state
       raise Unauthorized(action)
-    if tdef is None or tdef.getTriggerType() != TRIGGER_USER_ACTION:
+
+    transition = self._getOb(action, None)
+
+    if transition is None or transition.getTriggerType() != TRIGGER_USER_ACTION:
       msg = _(u"Transition '${action_id}' is not triggered by a user "
         u"action.", mapping={'action_id': action})
       raise WorkflowException(msg)
-    if not self._checkTransitionGuard(tdef, document, **kw):
+    if not self._checkTransitionGuard(transition, document, **kw):
       raise Unauthorized(action)
-    self._changeStateOf(document, tdef, kw)
+    self._changeStateOf(document, transition, kw)
 
   def _changeStateOf(self, document, tdef=None, kwargs=None):
     '''