Don't call ReactBridge.staticInit() on the main thread

Summary: Adding a hook to check if ReactBridge is initialized so we can avoid loading the .so on the main thread.

Reviewed By: fkgozali

Differential Revision: D17747958

fbshipit-source-id: 5969afa57dc1b446c03bc68eaa9e1385fe17c461

ReactAndroid/src/main/java/com/facebook/react/bridge/ReactBridge.java

@@ -18,6 +18,10 @@ public class ReactBridge {
 
   private static boolean sDidInit = false;
 
+  public static boolean isInitialized() {
+    return sDidInit;
+  }
+
   public static synchronized void staticInit() {
     if (sDidInit) {
       return;