Don't show focus frame on OS X

The focus frame needs a border around the view, but there isn't.

Change-Id: I9d7b206445be9f8e43bd9168ccea2075f4ac4bb7
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>

plugins/autotest/testresultspane.cpp

@@ -54,7 +54,9 @@ namespace Internal {
 
 ResultsTreeView::ResultsTreeView(QWidget *parent)
     : Utils::TreeView(parent)
-{}
+{
+    setAttribute(Qt::WA_MacShowFocusRect, false);
+}
 
 void ResultsTreeView::keyPressEvent(QKeyEvent *event)
 {