Bug 1432840 - Fix/enable eslint 'no-useless-return'

https://eslint.org/docs/rules/no-useless-return

neutrino-custom/lint.js

@@ -59,7 +59,6 @@ module.exports = neutrino => {
                     'no-use-before-define': 'off',
                     'no-useless-constructor': 'off',
                     'no-useless-escape': 'off',
-                    'no-useless-return': 'off',
                     'no-var': 'off',
                     'object-property-newline': 'off',
                     'object-shorthand': 'off',

ui/js/controllers/perf/graphs.js

@@ -472,7 +472,6 @@ perf.controller('GraphsCtrl', [
                 function updateSelectedItem() {
                     if (!$scope.selectedDataPoint) {
                         hideTooltip();
-                        return;
                     }
                 }