chore: use grunt to install optional phantomjs

connected to #3993

Gruntfile.js

@@ -31,6 +31,11 @@ module.exports = function(grunt) {
         },
       },
     },
+    run: {
+      optionalInstall: {
+        exec: 'npm install --no-save --silent karma-phantomjs-launcher phantomjs-prebuilt',
+      },
+    },
     eslint: {
       gruntfile: {
         src: 'Gruntfile.js',
@@ -211,6 +216,7 @@ module.exports = function(grunt) {
   });
 
   // These plugins provide necessary tasks.
+  grunt.loadNpmTasks('grunt-run');
   grunt.loadNpmTasks('grunt-browserify');
   grunt.loadNpmTasks('grunt-contrib-uglify');
   grunt.loadNpmTasks('grunt-eslint');
@@ -236,12 +242,14 @@ module.exports = function(grunt) {
   // Default task.
   grunt.registerTask('default', ['browserify']);
 
+  grunt.registerTask('phantomTests', ['run', 'karma:unit-once']);
+
   grunt.registerTask('test', [
     'eslint',
     process.env.JENKINS_HOME ? 'mochaTest:unit-xml' : 'mochaTest:unit',
     process.env.JENKINS_HOME && (/^win/.test(process.platform) ||
       /^s390x/.test(process.arch) || /^ppc64/.test(process.arch)) ?
-      'skip-karma' : 'karma:unit-once',
+      'skip-karma' : 'phantomTests',
   ]);
 
   // alias for sl-ci-run and `npm test`

package.json

@@ -82,6 +82,7 @@
     "grunt-eslint": "^21.0.0",
     "grunt-karma": "^2.0.0",
     "grunt-mocha-test": "^0.13.3",
+    "grunt-run": "^0.8.1",
     "karma": "^1.1.2",
     "karma-browserify": "^5.1.1",
     "karma-chrome-launcher": "^1.0.1",
@@ -90,13 +91,11 @@
     "karma-html2js-preprocessor": "^1.0.0",
     "karma-junit-reporter": "~1.0.0",
     "karma-mocha": "^1.1.1",
-    "karma-phantomjs-launcher": "^1.0.0",
     "karma-script-launcher": "^1.0.0",
     "loopback-boot": "^2.7.0",
     "loopback-context": "^1.0.0",
     "mocha": "^5.2.0",
     "nyc": "^10.1.2",
-    "phantomjs-prebuilt": "^2.1.7",
     "sinon": "^6.1.4",
     "sinon-chai": "^3.2.0",
     "strong-error-handler": "^3.0.0",