Force to use locale with extension if the created NumberFormat
is not a DecimalFormat.
Check the dynamic class id.
Guard DecimalFormat casting code

Bug: v8:9035
Change-Id: Id32a3f652b93ddfca82f95f30ad2107b364ee7fc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1536571Reviewed-by: Sathya Gunasekaran <gsathya@chromium.org>
Commit-Queue: Frank Tang <ftang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60452}