Reland parts of 'Use weak cells in map checks in polymorphic ICs'

This relands macroassembler instructions and weak cell caching and
does not include parts that caused "Linux ASan LSan" test failures.

BUG=v8:3663
LOG=N

Review URL: https://codereview.chromium.org/764003003

Cr-Commit-Position: refs/heads/master@{#25615}
23 files changed
tree: a7bef9c263b6c44cc4e1d167ecb39394a0af3bd8
  1. benchmarks/
  2. build/
  3. include/
  4. samples/
  5. src/
  6. test/
  7. testing/
  8. tools/
  9. .clang-format
  10. .gitignore
  11. AUTHORS
  12. BUILD.gn
  13. ChangeLog
  14. codereview.settings
  15. DEPS
  16. LICENSE
  17. LICENSE.strongtalk
  18. LICENSE.v8
  19. LICENSE.valgrind
  20. Makefile
  21. Makefile.android
  22. Makefile.nacl
  23. OWNERS
  24. PRESUBMIT.py
  25. README.md
  26. 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://code.google.com/p/v8/

Getting the Code

V8 Git repository: https://chromium.googlesource.com/v8/v8.git GitHub mirror: https://github.com/v8/v8-git-mirror

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/*