Add test for Object.craete(null) and prepare for release 2.2.3

.travis.yml

@@ -10,6 +10,7 @@ node_js:
   - '5'
   - '6'
   - '7'
+  - '8'
 script: "npm run test-travis"
 # Send coverage data to Coveralls
 after_script: "cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js"

package.json

@@ -1,6 +1,6 @@
 {
   "name": "immutability-helper",
-  "version": "2.2.2",
+  "version": "2.2.3",
   "description": "mutate a copy of data without changing the original source",
   "main": "index.js",
   "scripts": {

test.js

@@ -394,4 +394,9 @@ describe('update', function() {
     });
   }
 
+  it('supports objects without prototypes', function() {
+    var obj = Object.create(null);
+    expect(update.bind(null, obj, {$merge: {a: 'b'}})).toNotThrow()
+  });
+
 });