QmlDesigner: Use native text rendering for textfield

Change-Id: I01aea1d0bceeeb5f8942d79d234d674e3173ccfc
Reviewed-by: Brook Cronin <brook.cronin@qt.io>
Reviewed-by: Tim Jenssen <tim.jenssen@qt.io>

share/qtcreator/qmldesigner/statesEditorQmlSources/DesignerTextFieldStyle.qml

@@ -43,4 +43,5 @@ TextFieldStyle {
         color: Theme.color(Theme.FancyToolButtonSelectedColor)
         border.color: Theme.qmlDesignerBackgroundColorDarker()
     }
+    renderType: Text.NativeRendering
 }