Fix Promise#finaly shim regression and cover with tests

src/polyfills.js

@@ -1,6 +1,8 @@
 import 'babel-polyfill';
 import 'whatwg-fetch';
-import 'promise.prototype.finally';
+import { shim as shimPromiseFinaly } from 'promise.prototype.finally';
+
+shimPromiseFinaly();
 
 // allow :active styles in mobile Safary
 document.addEventListener('touchstart', () => {}, true);

tests/polyfills.test.js

@@ -0,0 +1,15 @@
+import expect from 'unexpected';
+
+describe('promise.prototype.finally', () => {
+    it('should be invoked after promise resolved', () =>
+        expect(new Promise((resolve) => {
+            Promise.resolve().finally(resolve)
+        }), 'to be fulfilled')
+    );
+
+    it('should be invoked after promise rejected', () =>
+        expect(new Promise((resolve) => {
+            Promise.reject().finally(resolve)
+        }), 'to be fulfilled')
+    );
+});