Update V8 to version 8.9.50.

Summary of changes available at:
https://chromium.googlesource.com/v8/v8/+log/08ac8ee5..12af0f03

Please follow these instructions for assigning/CC'ing issues:
https://v8.dev/docs/triage-issues

Please close rolling in case of a roll revert:
https://v8-roll.appspot.com/
This only works with a Google account.

CQ_INCLUDE_TRYBOTS=luci.chromium.try:linux-blink-rel
CQ_INCLUDE_TRYBOTS=luci.chromium.try:linux_optional_gpu_tests_rel
CQ_INCLUDE_TRYBOTS=luci.chromium.try:mac_optional_gpu_tests_rel
CQ_INCLUDE_TRYBOTS=luci.chromium.try:win_optional_gpu_tests_rel
CQ_INCLUDE_TRYBOTS=luci.chromium.try:android_optional_gpu_tests_rel

TBR=hablich@chromium.org,vahl@chromium.org,v8-waterfall-sheriff@grotations.appspotmail.com

Change-Id: I338497c22db4defb7496800032e94b893080d4ca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2561119Reviewed-by: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Commit-Queue: v8-ci-autoroll-builder <v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#831128}

DEPS

@@ -204,7 +204,7 @@ vars = {
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling V8
   # and whatever else without interference from each other.
-  'v8_revision': '08ac8ee506608963b749a7ec05b1dde7511d3996',
+  'v8_revision': '12af0f034a649a235be640e47205ef94d9916d4a',
   # Three lines of non-changing comments so that
   # the commit queue can handle CLs rolling swarming_client
   # and whatever else without interference from each other.