Merge branch 'add-object-assign-polyfill' into 'master'

Add Object.assign polyfill

Because PhantomJS

See merge request !8090

app/assets/javascripts/extensions/object.js.es6

+/* eslint-disable no-restricted-syntax */
+
+// Adapted from https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign#Polyfill
+if (typeof Object.assign !== 'function') {
+  Object.assign = function assign(target, ...args) {
+    if (target == null) { // TypeError if undefined or null
+      throw new TypeError('Cannot convert undefined or null to object');
+    }
+
+    const to = Object(target);
+
+    for (let index = 0; index < args.length; index += 1) {
+      const nextSource = args[index];
+
+      if (nextSource != null) { // Skip over if undefined or null
+        for (const nextKey in nextSource) {
+          // Avoid bugs when hasOwnProperty is shadowed
+          if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
+            to[nextKey] = nextSource[nextKey];
+          }
+        }
+      }
+    }
+    return to;
+  };
+}

spec/javascripts/extensions/object_spec.js.es6

+/*= require extensions/object */
+
+describe('Object extensions', () => {
+  describe('assign', () => {
+    it('merges source object into target object', () => {
+      const targetObj = {};
+      const sourceObj = {
+        foo: 'bar',
+      };
+      Object.assign(targetObj, sourceObj);
+      expect(targetObj.foo).toBe('bar');
+    });
+
+    it('merges object with the same properties', () => {
+      const targetObj = {
+        foo: 'bar',
+      };
+      const sourceObj = {
+        foo: 'baz',
+      };
+      Object.assign(targetObj, sourceObj);
+      expect(targetObj.foo).toBe('baz');
+    });
+  });
+});