TextEditor: Return hover handler priority by callback

...to get rid of the asynchronous code path.

Change-Id: I56377510440631b0be712333b2a4018717c86389
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/texteditor/texteditor.cpp

@@ -314,10 +314,8 @@ public:
         }
 
         // Cancel currently running checks
-        for (BaseHoverHandler *handler : m_handlers) {
-            if (handler->isAsyncHandler())
-                handler->cancelAsyncCheck();
-        }
+        for (BaseHoverHandler *handler : m_handlers)
+            handler->abort();
 
         // Update invocation data
         m_documentRevision = documentRevision;