Add tests for unordered args

test/Arguments should be able to be passed in in either order.js

@@ -0,0 +1,10 @@
+import test from 'ava';
+import browserEnv from '../dist';
+
+test(t => {
+  t.is(typeof navigator, 'undefined');
+  const returnValue = browserEnv(['navigator'], { userAgent: 'first' });
+  t.is(navigator.userAgent, 'first');
+  const secondReturnValue = browserEnv({ userAgent: 'second' }, ['navigator']);
+  t.is(navigator.userAgent, 'second');
+});