question engine: MDL-17651 this context is not used anywhere, so remove it.

(There was a bug in the get_context_instance call.)

question/type/questiontype.php

@@ -902,15 +902,6 @@ class default_questiontype {
         global $CFG;
         $isgraded = question_state_is_graded($state->last_graded);
 
-        // Get the context we should use to check permissions.
-        if (!empty($cmoptions->id)) {
-            $context = get_context_instance(CONTEXT_MODULE, $cmoptions->id);
-        } else if (!empty($cmoptions->course)) {
-            $context = get_context_instance(CONTEXT_COURSE, $cmoptions->course);
-        } else {
-            $context = null;
-        }
-
         if (isset($question->randomquestionid)) {
             $actualquestionid = $question->randomquestionid;
         } else {