Check for Android using userAgent

Modern Android systems seem to report "Linux" for navigator.platform, so
we can no longer rely on that.

core/util/browser.js

@@ -94,7 +94,8 @@ export function isIOS() {
 }
 
 export function isAndroid() {
-    return !!(/android/i).exec(navigator.platform);
+    /* Android sets navigator.platform to Linux :/ */
+    return !!navigator.userAgent.match('Android ');
 }
 
 export function isChromeOS() {