Add dynamic type for javascript arguments passed over bridge with unkown type

Reviewed By: astreet

Differential Revision: D4380882

fbshipit-source-id: f1b9fb9cf727d003dcc2264626e75fc300a47dee

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

@@ -88,6 +88,11 @@ public class JavaOnlyArray implements ReadableArray, WritableArray {
     return (JavaOnlyMap) mBackingList.get(index);
   }
 
+  @Override
+  public Dynamic getDynamic(int index) {
+    return new DynamicFromArray(this, index);
+  }
+
   @Override
   public ReadableType getType(int index) {
     Object object = mBackingList.get(index);