The class is dead code, and has not been used for years. I tried to
deprecate the class first, but this caused build errors on GCC [1].
That's why this CL just deletes the class. Deleting the class is okay
because this class was part of the original implementation of streaming
compilation. There is only a single embedder who uses streaming
compilation, which is Chrome, and Chrome switched to the new API
already years ago. If there were other embedders that use this class,
then this embedder would already have no working implementation of
streaming compilation for years.

R=adamk@chromium.org

Bug: v8:12926
Change-Id: I3342167245822cf8ee52d9632cba236fb1b0646c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3714236
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81421}