This changes Generate_ContinueToBuiltinHelper to generate code to load
the builtin address directly from the builtins table rather than going
via the executable code in the trampoline's code object.

The set up for Generate_ContinueToBuiltinHelper is changed so that the
builtin index is stored on the stack in place of the builtin Code
object which is no longer needed.

Bug: v8:9338
Change-Id: I83f66af99fb27f131fc39ff426fdca4b1d674b70
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1648155
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Sigurd Schneider <sigurds@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62170}