Reland "[heap] Set read-only space's and its pages' heap_ to null."

Seems like the CodeBuilder CL actually caused this.

This is a reland of 964edc251fce2dfa81b3ba695009195e3f336d3e

Original change's description:
> [heap] Set read-only space's and its pages' heap_ to null.
>
> Various small changes are required to enable this.
>
> HeapObject::GetReadOnlyRoots no longer uses the Space's heap when
> possible (see comment in ReadOnlyHeap::GetReadOnlyRoots definition).
> This requires that ReadOnlyRoots be construct-able using a raw pointer
> to the read-only space's roots array.
>
> Global read-only heap state is now cleared by tests where appropriate
> and extra DCHECKs in ReadOnlyHeap::SetUp should make catching future
> issues easier.
>
> String padding is now always cleared just before read-only space is
> sealed when not deserializing.
>
> Change-Id: I7d1db1c11567be5df06ff7066f3a699125f8b372
> Bug: v8:7464
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1535830
> Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Dan Elphick <delphick@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#61188}

Bug: v8:7464
Change-Id: If75bbd16c2e2af5b80cd60811dfd7866f8be8309
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1599186
Commit-Queue: Maciej Goszczycki <goszczycki@google.com>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Dan Elphick <delphick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#61323}
20 files changed
tree: 69d2bd536cef8108b723f6744f18ab79b1893f78
  1. benchmarks/
  2. build_overrides/
  3. custom_deps/
  4. docs/
  5. gni/
  6. include/
  7. infra/
  8. samples/
  9. src/
  10. test/
  11. testing/
  12. third_party/
  13. tools/
  14. .clang-format
  15. .clang-tidy
  16. .editorconfig
  17. .git-blame-ignore-revs
  18. .gitattributes
  19. .gitignore
  20. .gn
  21. .vpython
  22. .ycm_extra_conf.py
  23. AUTHORS
  24. BUILD.gn
  25. ChangeLog
  26. CODE_OF_CONDUCT.md
  27. codereview.settings
  28. DEPS
  29. LICENSE
  30. LICENSE.fdlibm
  31. LICENSE.strongtalk
  32. LICENSE.v8
  33. LICENSE.valgrind
  34. OWNERS
  35. PRESUBMIT.py
  36. README.md
  37. snapshot_toolchain.gni
  38. WATCHLISTS
README.md

V8 JavaScript Engine

V8 is Google's open source JavaScript engine.

V8 implements ECMAScript as specified in ECMA-262.

V8 is written in C++ and is used in Google Chrome, the open source browser from Google.

V8 can run standalone, or can be embedded into any C++ application.

V8 Project page: https://v8.dev/docs

Getting the Code

Checkout depot tools, and run

    fetch v8

This will checkout V8 into the directory v8 and fetch all of its dependencies. To stay up to date, run

    git pull origin
    gclient sync

For fetching all branches, add the following into your remote configuration in .git/config:

    fetch = +refs/branch-heads/*:refs/remotes/branch-heads/*
    fetch = +refs/tags/*:refs/tags/*

Contributing

Please follow the instructions mentioned at v8.dev/docs/contribute.