QmlProfiler: remove V8 tab

V8 is gone long enough to stop supporting it.

Change-Id: If086925359097a69ffab2b2eba4de6f63bd5195e
Reviewed-by: Ulf Hermann <ulf.hermann@theqtcompany.com>
Reviewed-by: Alessandro Portale <alessandro.portale@theqtcompany.com>

src/plugins/qmlprofiler/qmlprofilerclientmanager.h

@@ -77,7 +77,6 @@ private slots:
     void retryMessageBoxFinished(int result);
 
     void qmlComplete(qint64 maximumTime);
-    void v8Complete();
 
     void profilerStateChanged();
     void clientRecordingChanged();