QML designer: Fix compilation for namespaced Qt.

src/plugins/qmldesigner/components/propertyeditor/contextpanewidgetimage.h

@@ -3,10 +3,11 @@
 
 #include <QWidget>
 
+QT_BEGIN_NAMESPACE
 namespace Ui {
     class ContextPaneWidgetImage;
 }
-
+QT_END_NAMESPACE
 
 namespace QmlJS {
     class PropertyReader;

src/plugins/qmldesigner/components/propertyeditor/contextpanewidgetrectangle.h

@@ -3,9 +3,11 @@
 
 #include <QWidget>
 
+QT_BEGIN_NAMESPACE
 namespace Ui {
     class ContextPaneWidgetRectangle;
 }
+QT_END_NAMESPACE
 
 namespace QmlJS {
     class PropertyReader;