CppEditor: Do not cancel highlighter on user interaction

e.g. changing cursor position or editing text.

CPPEditorWidget::updateUses() does not depend on the highlighter, but
only on the semantic info update.

Task-number: QTCREATORBUG-11367
Change-Id: Ia9f5ed7c2adc6899995a5d966a20e45b2f87d9e3
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/plugins/cppeditor/cppeditor.cpp

@@ -1158,11 +1158,6 @@ void CPPEditorWidget::updateOutlineToolTip()
 
 void CPPEditorWidget::updateUses()
 {
-    if (m_highlightWatcher) {
-        m_highlightWatcher->cancel();
-        m_highlightWatcher.reset();
-    }
-
     // Block premature semantic info calculation when editor is created.
     if (m_modelManager && m_modelManager->cppEditorSupport(editor())->initialized())
         m_updateUsesTimer->start();