ff shadow dom support

app/content-scripts/rewards/__tests__/HotDog.jsx

@@ -0,0 +1,8 @@
+import React from 'react';
+import renderer from 'react-test-renderer';
+import { MemoryRouter } from 'react-router';
+import HotDog from '../HotDog';
+
+global.t = function (str) {
+	return str;
+};

app/content-scripts/rewards/index.jsx

@@ -67,7 +67,7 @@ class RewardsApp {
 	}
 
 	start() {
-		if (BROWSER_INFO.name === 'chrome') {
+		if (document.head.createShadowRoot || document.head.attachShadow) {
 			this.renderShadow();
 		} else {
 			// use iframe to encapsulate CSS - fallback for everything else besides chrome