Fix Promise argument assertion to take into account executorTokenOffset.

Summary:In the code that extracts and validates arguments from a `ReactMethod`, there is verification that if a method contains a Promise in it's list of arguments that it must come last. This fix makes sure that the `executorTokenOffset` is taken into account when asserting that condition.
Closes #6633

Differential Revision: D3143207

fb-gh-sync-id: ae9ebd9d829f88993f9951c4cb2452b3f7618476
fbshipit-source-id: ae9ebd9d829f88993f9951c4cb2452b3f7618476

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

@@ -189,7 +189,8 @@ private ArgumentExtractor[] buildArgumentExtractors(Class[] paramTypes) {
 
       ArgumentExtractor[] argumentExtractors = new ArgumentExtractor[paramTypes.length - executorTokenOffset];
       for (int i = 0; i < paramTypes.length - executorTokenOffset; i += argumentExtractors[i].getJSArgumentsNeeded()) {
-        Class argumentClass = paramTypes[i + executorTokenOffset];
+        int paramIndex = i + executorTokenOffset;
+        Class argumentClass = paramTypes[paramIndex];
         if (argumentClass == Boolean.class || argumentClass == boolean.class) {
           argumentExtractors[i] = ARGUMENT_EXTRACTOR_BOOLEAN;
         } else if (argumentClass == Integer.class || argumentClass == int.class) {
@@ -205,7 +206,7 @@ private ArgumentExtractor[] buildArgumentExtractors(Class[] paramTypes) {
         } else if (argumentClass == Promise.class) {
           argumentExtractors[i] = ARGUMENT_EXTRACTOR_PROMISE;
           Assertions.assertCondition(
-              i == paramTypes.length - 1, "Promise must be used as last parameter only");
+              paramIndex == paramTypes.length - 1, "Promise must be used as last parameter only");
           mType = METHOD_TYPE_REMOTE_ASYNC;
         } else if (argumentClass == ReadableMap.class) {
           argumentExtractors[i] = ARGUMENT_EXTRACTOR_MAP;
@@ -361,7 +362,7 @@ public void onReactBridgeInitialized(ReactBridge bridge) {
   public void onCatalystInstanceDestroy() {
     // do nothing
   }
-  
+
   @Override
   public boolean supportsWebWorkers() {
     return false;