Revert "drop browserify". Drop babelify. Tuning build matrix

This reverts commit 8854c54.

.travis.yml

@@ -2,24 +2,29 @@ sudo: false
 
 language: node_js
 
-node_js:
-  - "4.0"
-  - "5.0"
-  - "6.0"
-  - "7.0"
-  - "8.0"
-  - "9.0"
-  - lts/*
-  - node
+stages:
+  - lint
+  - test
 
 jobs:
   include:
     - stage: lint
       node_js: node
       script: npm run lint
     - stage: test
+      node_js:
+        - "4.0"
+        - "5.0"
+        - "6.0"
+        - "7.0"
+        - "8.0"
+        - "9.0"
+        - lts/*
+        - node
       script: npm run test
-    - node_js: node
+    - stage: test
+      node_js: node
+      env: BROWSER=true # Just mark in the Travis UI
       script: npm run browser
 
 after_success:

karma.conf.js

@@ -77,14 +77,22 @@ module.exports = function(config) {
   config.set(withBrowserStack({
     // frameworks to use
     // available frameworks: https://npmjs.org/browse/keyword/karma-adapter
-    frameworks: ['mocha'],
+    frameworks: ['browserify', 'mocha'],
 
     // list of files / patterns to load in the browser
     files: [
       'lib/**/*.js',
       'test/**/*.js',
     ],
 
+    // preprocess matching files before serving them to the browser
+    // available preprocessors: https://npmjs.org/browse/keyword/karma-preprocessor
+    preprocessors: {
+      'lib/**/*.js':  ['browserify'],
+      'test/**/*.js': ['browserify'],
+    },
+    browserify: { debug: true },
+
     // test results reporter to use
     // possible values: 'dots', 'progress'
     // available reporters: https://npmjs.org/browse/keyword/karma-reporter

package.json

@@ -10,11 +10,13 @@
     "safe-stable-stringify": "^1.0.1"
   },
   "devDependencies": {
+    "browserify": "^16.1.1",
     "chai": "^4.1.2",
     "chai-json-schema": "^1.5.0",
     "coveralls": "^3.0.0",
     "eslint": "^4.19.0",
     "karma": "^2.0.0",
+    "karma-browserify": "^5.2.0",
     "karma-browserstack-launcher": "^1.3.0",
     "karma-mocha": "^1.3.0",
     "karma-mocha-reporter": "^2.2.5",