This flag describes that the memory defined in a wasm module has a
maximum size. Therefore I think kHasMaximumFlag is more appropriate.

R=titzer@chromium.org

Bug: v8:6921
Change-Id: Ie794d670f74e7f1f9a42822e2f774da85aaaaa4b
Reviewed-on: https://chromium-review.googlesource.com/718198Reviewed-by: Ben Titzer <titzer@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48517}