AssembleCode used CcTest::i_isolate() to load the isolate, however this
might not be the isolate that should be used. Therefore take the isolate
as an explicit argument.

Note that this changes behavior of ExecuteMemoryAccess in
test-sync-primitives-arm.cc. I think this test inadvertently created
the assembly code in the isolate of another thread, while it didn't
use the isolate it sets the handle scope up for.

This change is required for relanding https://crrev.com/c/2543399.

Bug: v8:10315
Change-Id: I754f4b45cec93727309fa73723011afe976f3689
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2546682Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71257}