[OSX] Buildfix: Classes used with templates must be fully qualified.

Change-Id: Idf1cd3990e2cfd9e2ed3b017370e689c1126bb48
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>

src/webenginewidgets/render_widget_host_view_qt_delegate_widget.cpp

@@ -46,6 +46,7 @@
 #include <QSGAbstractRenderer>
 #include <QSGEngine>
 #include <QSGNode>
+#include <QWindow>
 
 static const int MaxTooltipLength = 1024;
 

src/webenginewidgets/render_widget_host_view_qt_delegate_widget.h

@@ -40,19 +40,16 @@
 #include "render_widget_host_view_qt_delegate.h"
 #include "web_contents_adapter_client.h"
 
+#include <QSGAbstractRenderer>
+#include <QSGEngine>
+#include <QSGNode>
+
 #if (QT_VERSION < QT_VERSION_CHECK(5, 4, 0))
 #include <QtWidgets/private/qopenglwidget_p.h>
 #else
 #include <QtWidgets/QOpenGLWidget>
 #endif
 
-QT_BEGIN_NAMESPACE
-class QSGAbstractRenderer;
-class QSGEngine;
-class QSGRootNode;
-class QWindow;
-QT_END_NAMESPACE
-
 class RenderWidgetHostViewQtDelegateWidget : public QOpenGLWidget, public RenderWidgetHostViewQtDelegate {
     Q_OBJECT
 public: