Add defensive check for result returned after JNI function calls

Summary:
Added method which checks if value(methodId, fieldId, class ...) returned by JNI functions (getMethod, getField, getClass ...) is valid or not and throw exception if they are not valid

##Changelog:
[Internal][Yoga] Add defensive check for result returned after JNI calls

Reviewed By: astreet

Differential Revision: D18745718

fbshipit-source-id: 2af26eda15fbe7834e1c9b274deeed4f106274ab

java/jni/corefunctions.h

@@ -47,6 +47,8 @@ void logErrorMessageAndDie(const char* message);
  */
 void assertNoPendingJniException(JNIEnv* env);
 
+void assertNoPendingJniExceptionIf(JNIEnv* env, bool condition);
+
 } // namespace vanillajni
 } // namespace yoga
 } // namespace facebook