fix: android looper

Author: nattb8

Plugins/Android/Gree-Android/webview-nofragment/src/main/java/com/immutable/gree/unitywebview/CWebViewPluginNoUi.java

@@ -86,6 +86,9 @@ public static boolean isDestroyed(final Activity a) {
     }
 
     public CWebViewPluginNoUi() {
+        if (Looper.myLooper() == null) {
+            Looper.prepare();
+        }
         unityHandler = new Handler(Looper.myLooper());
     }