applets/batterymonitor: fix CompactRepresentation

f9e39815dc introduced a few regressions by
blowing away the custom CompactRepresentation when there are no
batteries. This introduced a race condition that sometimes set the icon
incorrectly and also broke scrolling on the applet to change the volume.

This commit fixes those issues by using the existing infrastructure for
the CompactPepresentation, but simply swapping out its custom battery
icon for normal icon when there are no batteries.

applets/batterymonitor/package/contents/ui/CompactRepresentation.qml

@@ -18,6 +18,7 @@ MouseArea {
     property real itemSize: Math.min(root.height, root.width/view.count)
     readonly property bool isConstrained: plasmoid.formFactor === PlasmaCore.Types.Vertical || plasmoid.formFactor === PlasmaCore.Types.Horizontal
     property real brightnessError: 0
+    property bool hasBatteries: true
 
     onClicked: plasmoid.expanded = !plasmoid.expanded
 
@@ -44,8 +45,17 @@ MouseArea {
         batterymonitor.screenBrightness = Math.max(minimumBrightness, Math.min(maximumBrightness, newBrightness));
     }
 
+    // "No Batteries" case
+    PlasmaCore.IconItem {
+        anchors.fill: parent
+        visible: !root.hasBatteries
+        source: plasmoid.icon
+    }
+
+    // We have any batteries; show their status
     //Should we consider turning this into a Flow item?
     Row {
+        visible: root.hasBatteries
         anchors.centerIn: parent
         Repeater {
             id: view

applets/batterymonitor/package/contents/ui/main.qml

@@ -219,11 +219,9 @@ Item {
         }
     }
 
-    Component {
-        id: batteryCompact
-        CompactRepresentation {}
+    Plasmoid.compactRepresentation: CompactRepresentation {
+        hasBatteries: batterymonitor.hasBatteries
     }
-    Plasmoid.compactRepresentation: hasBatteries ? batteryCompact : null
 
 
     readonly property bool isBrightnessAvailable: pmSource.data["PowerDevil"] && pmSource.data["PowerDevil"]["Screen Brightness Available"] ? true : false