Reuse message when updating redbox with symbolicated JS error

Summary:
On iOS, `RCTRedBox` will not update the displayed stack trace if the message string sent with the update differs from the original error message. As JS errors are shown in two stages - before and after symbolication - there was previously a case where the message would differ between the two `updateExceptionMessage` calls, blocking the update and leaving only the unsymbolicated trace visible. This diff fixes that.

Longer term, we should also change `RCTRedBox`'s logic to rely on the JS-provided `exceptionID` instead of the message string - similar to what we do on Android.

Changelog:
[iOS] [Fixed] - Fix redbox JS symbolication when adding JS engine tag to the message

Reviewed By: sahrens

Differential Revision: D15202524

fbshipit-source-id: 237fc090e88b0c609865e0aed842d6a609c1239a

Libraries/Core/ExceptionsManager.js

@@ -49,7 +49,7 @@ function reportException(e: ExtendedError, isFatal: boolean) {
               frame => frame.file.match(INTERNAL_CALLSITES_REGEX) === null,
             );
             ExceptionsManager.updateExceptionMessage(
-              e.message,
+              message,
               stackWithoutInternalCallsites,
               currentExceptionID,
             );