QmlDesigner: Fix 2 "property not defined" qml errors in texture editor

...by setting the context properties in the constructor.

Also remove some unused includes.

Change-Id: Ibb7901b79b5a97552fee7cf8428f35293451dbc4
Reviewed-by: Ali Kianian <ali.kianian@qt.io>

src/plugins/qmldesigner/components/textureeditor/textureeditorqmlbackend.cpp

@@ -5,7 +5,6 @@
 
 #include "assetimageprovider.h"
 #include "bindingproperty.h"
-#include "documentmanager.h"
 #include "nodemetainfo.h"
 #include "propertyeditorvalue.h"
 #include "qmldesignerconstants.h"
@@ -16,17 +15,11 @@
 
 #include <coreplugin/icore.h>
 
-#include <qmldesignerutils/hdrimage.h>
-#include <utils/algorithm.h>
 #include <utils/environment.h>
-#include <utils/fileutils.h>
 #include <utils/qtcassert.h>
 #include <utils/stylehelper.h>
 
-#include <QDir>
-#include <QFileInfo>
 #include <QQuickImageProvider>
-#include <QQuickItem>
 #include <QQuickWidget>
 #include <QVector2D>
 #include <QVector3D>
@@ -58,6 +51,8 @@ TextureEditorQmlBackend::TextureEditorQmlBackend(TextureEditorView *textureEdito
     m_contextObject->setBackendValues(&m_backendValuesPropertyMap);
     m_contextObject->setModel(textureEditor->model());
     context()->setContextObject(m_contextObject.get());
+    context()->setContextProperty("hasTexture", QVariant(false));
+    context()->setContextProperty("modelNodeBackend", &m_backendModelNode);
 
     QObject::connect(&m_backendValuesPropertyMap, &DesignerPropertyMap::valueChanged,
                      textureEditor, &TextureEditorView::changeValue);