QmlDesigner: prepare Sections for use as a delegate

Change-Id: Ieeddea3d813f13cb7018d6611156f1f98b69e6be
Reviewed-by: Marco Bubke <marco.bubke@digia.com>

share/qtcreator/qmldesigner/propertyEditorQmlSources/HelperWidgets/Section.qml

@@ -36,8 +36,6 @@ Item {
     id: section
     property alias caption: label.text
 
-    anchors.left: parent.left
-    anchors.right: parent.right
     clip: true
 
     Rectangle {