This introduces a utility function on code stub assembler to check that
a map has given prototype object map. In addition, if constant field
tracking is active, it will check that a given field is still constant
(typically a function that is assumed not to be patched).

This also fixes a fast path check in regexp C++ code to properly detect
that "exec" function was modified on RegExp's prototype when constant
field tracking is on.

Bug: v8:5495, v8:8361
Change-Id: I98476db46ba4633124cf1437be90aea3585ce978
Reviewed-on: https://chromium-review.googlesource.com/c/1297954
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Cr-Commit-Position: refs/heads/master@{#57290}