Normalize bar icon size and alignment

shell/plugins/panels/power/Panel.qml

@@ -278,9 +278,8 @@ Panel {
     id: button
     anchors.fill: parent
     bar: root.bar
-    text: root.showPercentage && !vertical
-      ? Math.round(root.batteryFraction * 100) + "% " + root.batteryIcon()
-      : root.batteryIcon()
+    text: root.batteryIcon()
+    labelText: root.showPercentage && !vertical ? Math.round(root.batteryFraction * 100) + "%" : ""
     slotSize: Style.bar.iconSlot * (root.showPercentage && !vertical ? 2 : 1)
     tooltipText: ""
     onPressed: function(b) {