QmlDesigner: There is no textColor property in the Button

Change-Id: Ic45416d1ad187520dc4771192e621d7e44ee360f
Reviewed-by: Thomas Hartmann <Thomas.Hartmann@digia.com>

src/plugins/qmldesigner/componentsplugin/Controls/ButtonSpecifics.qml

@@ -130,12 +130,6 @@ QWidget {
                     }
                 }
 
-                ColorGroupBox {
-                    caption: qsTr("Text color")
-                    finished: finishedNotify
-                    backendColor: backendValues.textColor
-                }
-
                 QWidget {
                     layout: HorizontalLayout {
                         Label {