QmlDesigner.PropertyEditor: Fix GeometrySection

This fixes a regression introduced by
commit 1da0d018

.

Task-number: QTCREATORBUG-12501
Change-Id: I96dd1c19afa6b6b0a56ef5f6ea5e01272aa1b774
Reviewed-by: Tim Jenssen <tim.jenssen@digia.com>

share/qtcreator/qmldesigner/propertyEditorQmlSources/QtQuick/GeometrySection.qml

@@ -45,6 +45,9 @@ import QtQuick.Layouts 1.0
 Section {
     caption: qsTr("Geometry")
 
+    anchors.left: parent.left
+    anchors.right: parent.right
+
     SectionLayout {
         rowSpacing: 4
         rows: 2