The current error message assumes all classes are named, which results
in a double space and awkward wording when calling an anonymous class
constructor.

Bug: v8:10025
Change-Id: Ibe913152c0816cbbaaa0c7a88db4e415762ae9bb
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1947336
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Auto-Submit: Shu-yu Guo <syg@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65354}