Quick: Document javaScriptConsoleMessage

Change-Id: Iaf5a9c7915cdce36fe3219dd686059973d1a6251
Reviewed-by: Michael Brüning <michael.bruning@theqtcompany.com>

src/webengine/api/qquickwebengineview.cpp

@@ -441,7 +441,6 @@ bool QQuickWebEngineViewPrivate::isFullScreen() const
 void QQuickWebEngineViewPrivate::javaScriptConsoleMessage(JavaScriptConsoleMessageLevel level, const QString& message, int lineNumber, const QString& sourceID)
 {
     Q_Q(QQuickWebEngineView);
-    Q_UNUSED(level);
     Q_EMIT q->javaScriptConsoleMessage(static_cast<QQuickWebEngineView::JavaScriptConsoleMessageLevel>(level), message, lineNumber, sourceID);
 }
 

src/webengine/doc/src/qquickwebengineview_lgpl.qdoc

@@ -312,6 +312,18 @@
     The corresponding handler is onLinkHovered.
 */
 
+/*!
+    \qmlsignal WebEngineView::javaScriptConsoleMessage(JavaScriptConsoleMessageLevel level, message, lineNumber, sourceID)
+    This signal is emitted when a JavaScript program tries to print a \a message to the web browser's console.
+
+    For example in case of evaluation errors the source URL may be provided in \a sourceID as well as the \a lineNumber.
+
+    \a level indicates the severity of the event that triggered the message, i.e. if it
+    was triggered by an error or a less severe event.
+
+    The corresponding handler is onJavaScriptConsoleMessage.
+*/
+
 /*!
     \qmlsignal WebEngineView::newViewRequested(request)