kcms/rules: Some QML clean-ups

- Remove unnecessary bindings to enabled: Properties that are not
  enabled are not shown in the list anyway, and it fixes QML warnings:

  RuleItemDelegate.qml:16:5: Unable to assign [undefined] to bool
  RuleItemDelegate.qml:93:17: Unable to assign [undefined] to bool

- Remove unnecessary colorSet
- Port away from javascript `var`
- Remove outdated comment

src/kcms/rules/ui/RuleItemDelegate.qml

@@ -13,10 +13,6 @@ import org.kde.kcmutils as KCM
 QQC2.ItemDelegate {
     id: ruleDelegate
 
-    property bool ruleEnabled: model.enabled
-
-    Kirigami.Theme.colorSet: Kirigami.Theme.View
-
     width: ListView.view.width
     highlighted: false
     hoverEnabled: false
@@ -76,7 +72,6 @@ QQC2.ItemDelegate {
                 Layout.alignment: Qt.AlignVCenter
 
                 visible: count > 0
-                enabled: ruleEnabled
 
                 model: policyModel
                 onActivated: {
@@ -90,8 +85,6 @@ QQC2.ItemDelegate {
                 Layout.fillWidth: true
                 Layout.alignment: Qt.AlignVCenter | Qt.AlignRight
 
-                enabled: model.enabled
-
                 ruleValue: model.value
                 ruleOptions: model.options
                 controlType: model.type

src/kcms/rules/ui/RulesEditor.qml

@@ -297,7 +297,7 @@ KCM.ScrollViewKCM {
             case RuleItem.Option:
                 return options.textOfValue(value);
             case RuleItem.NetTypes:
-                var selectedValue = value.toString(2).length - 1;
+                const selectedValue = value.toString(2).length - 1;
                 return options.textOfValue(selectedValue);
             case RuleItem.OptionList:
                 return Array.from(value, item => options.textOfValue(item) ).join(", ");
@@ -309,7 +309,7 @@ KCM.ScrollViewKCM {
         id: enabledRulesModel
         sourceModel: kcm.rulesModel
         filterRowCallback: (source_row, source_parent) => {
-            var index = sourceModel.index(source_row, 0, source_parent);
+            const index = sourceModel.index(source_row, 0, source_parent);
             return sourceModel.data(index, RulesModel.EnabledRole);
         }
     }
@@ -325,13 +325,13 @@ KCM.ScrollViewKCM {
 
         filterString: searchField.text.trim().toLowerCase()
         filterRowCallback: (source_row, source_parent) => {
-            var index = sourceModel.index(source_row, 0, source_parent);
+            const index = sourceModel.index(source_row, 0, source_parent);
 
-            var hasSuggestion = sourceModel.data(index, RulesModel.SuggestedValueRole) != null;
-            var isOptional = sourceModel.data(index, RulesModel.SelectableRole);
-            var isEnabled = sourceModel.data(index, RulesModel.EnabledRole);
+            const hasSuggestion = sourceModel.data(index, RulesModel.SuggestedValueRole) != null;
+            const isOptional = sourceModel.data(index, RulesModel.SelectableRole);
+            const isEnabled = sourceModel.data(index, RulesModel.EnabledRole);
 
-            var showItem = hasSuggestion || (!onlySuggestions && isOptional && !isEnabled);
+            const showItem = hasSuggestion || (!onlySuggestions && isOptional && !isEnabled);
 
             if (!showItem) {
                 return false;

src/kcms/rules/ui/ValueEditor.qml

@@ -124,7 +124,7 @@ Loader {
             multipleChoice: true
 
             onActivated: {
-                let selectionList = []
+                const selectionList = []
                 for (let i = 0; i < count; i++) {
                     if (selectionMask & (1 << i)) {
                         selectionList.push(model.data(model.index(i,0), Qt.UserRole))

src/kcms/rules/ui/main.qml

@@ -14,7 +14,6 @@ import org.kde.kirigami 2.12 as Kirigami
 KCM.ScrollViewKCM {
     id: rulesListKCM
 
-    // FIXME: ScrollViewKCM.qml:73:13: QML Control: Binding loop detected for property "implicitHeight"
     implicitWidth: Kirigami.Units.gridUnit * 35
     implicitHeight: Kirigami.Units.gridUnit * 35