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Bill Budge 213016d65a Revert "[builtins] Clean up the use of class_name / ES5 [[Class]]"
This reverts commit 29c1eab92e.

Reason for revert: Causes Blink test failures:
https://ci.chromium.org/p/v8/builders/ci/V8%20Blink%20Linux/4222

Original change's description:
> [builtins] Clean up the use of class_name / ES5 [[Class]]
> 
> Before ES2015, the ES spec had a [[Class]] internal slot for all
> objects, which Object.prototype.toString() would use to figure the
> returned string. Post-ES2015, the [[Class]] slot was removed in spec for
> all objects, with the @@toStringTag well-known symbol the proper way to
> change Object.prototype.toString() output.
> 
> At the time, spec-identical handling without the use of [[Class]] was
> implemented in V8 for all objects other than API objects, where issues
> with the Web IDL spec [1] prevented Blink, and hence V8, to totally
> migrate to @@toStringTag. However, since 2016 [2] Blink has been setting
> @@toStringTag on API class prototypes to manage the
> Object.prototype.toString() output, so the legacy [[Class]] handling in
> V8 has not been necessary for the past couple of years.
> 
> This CL removes the remaining legacy [[Class]] handling in
> Object.prototype.toString(), JSReceiver::class_name(), and
> GetConstructorName(). However, it does not remove the class_name field
> in FunctionTemplateInfo, as it is still used for the `name` property of
> created functions.
> 
> This CL also cleans up other places in the codebase that still reference
> [[Class]].
> 
> This change should have minimal impact on web-compatibility. For the
> change to be observable, a script must do one of the following:
> 
> 1. delete APIConstructor.prototype[Symbol.toStringTag];
> 2. Object.setPrototypeOf(apiObject, somethingElse);
> 
> Before this CL, these changes will not change the apiObject.toString()
> output. But after this CL, they will make apiObject.toString() show
> "[object Object]" (in the first case) or the @@toStringTag of the other
> prototype (in the latter case).
> 
> However, both are deemed unlikely. @@toStringTag is not well-known
> feature of JavaScript, nor does it get tampered much on API
> constructors. In the second case, setting the prototype of an API object
> would effectly render the object useless, as all its methods (including
> property getters/setters) would no longer be accessible.
> 
> Currently, @@toStringTag-based API object branding is not yet
> implemented by other browsers. This V8 bug in particular has been an
> impediment to standardizing toString behavior. Fixing this bug will
> unblock [3] and lead to a better Web IDL spec, and better toString()
> compatibility for all.
> 
> [1]: https://www.w3.org/Bugs/Public/show_bug.cgi?id=28244
> [2]: https://crrev.com/909c0d7d5a53c8526ded351683c65ea7d17531d4
> [3]: https://github.com/heycam/webidl/pull/357
> 
> Bug: chromium:793406
> Cq-Include-Trybots: luci.chromium.try:linux-rel
> Change-Id: Iceded24e37afa2646ec385d5018909f55b177f93
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2146996
> Commit-Queue: Timothy Gu <timothygu@chromium.org>
> Reviewed-by: Toon Verwaest <verwaest@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#67327}

TBR=verwaest@chromium.org,timothygu@chromium.org

Change-Id: I678d2ffc1064b1d1ddb62024cc23c6c41b216ef4
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: chromium:793406
Cq-Include-Trybots: luci.chromium.try:linux-rel
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2163956
Reviewed-by: Bill Budge <bbudge@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67349}
2020-04-24 00:02:14 +00:00
build_overrides [tracing] Migrate tracing to Perfetto track events 2020-04-17 21:31:24 +00:00
custom_deps Use relative paths to OWNERS files 2019-08-12 13:52:52 +00:00
docs Add OWNERS for docs/ 2019-05-15 12:06:15 +00:00
gni [tracing] Migrate tracing to Perfetto track events 2020-04-17 21:31:24 +00:00
include cppgc: Add public target to build against 2020-04-21 12:48:23 +00:00
infra Configure ARM builder for CFI protection testing 2020-04-17 09:15:56 +00:00
samples [api] Create v8::String::NewFromLiteral that returns Local<String> 2020-03-09 12:02:07 +00:00
src Revert "[builtins] Clean up the use of class_name / ES5 [[Class]]" 2020-04-24 00:02:14 +00:00
test Revert "[builtins] Clean up the use of class_name / ES5 [[Class]]" 2020-04-24 00:02:14 +00:00
testing Roll v8/third_party/googletest/src/ 10b1902d8..e3f0319d8 (43 commits) 2020-04-15 07:23:10 +00:00
third_party [tracing] Migrate tracing to Perfetto track events 2020-04-17 21:31:24 +00:00
tools [wasm] Update spec tests 2020-04-22 15:26:15 +00:00
.clang-format [clang-format] Don't derive pointer alignment 2017-01-17 09:28:19 +00:00
.clang-tidy [tool] Remove unfixed clang-tidy warnings to ease use. 2018-10-26 07:40:32 +00:00
.editorconfig Add .editorconfig 2017-07-28 13:39:24 +00:00
.flake8 Add .flake8 to allow for python style checking. 2019-07-19 21:44:03 +00:00
.git-blame-ignore-revs [infra] Update .git-blame-ignore-revs 2020-03-03 12:59:13 +00:00
.gitattributes .gitattributes: Mark minified emscripten js files as -diff 2018-09-19 16:27:10 +00:00
.gitignore [tracing] Migrate tracing to Perfetto track events 2020-04-17 21:31:24 +00:00
.gn [build] Dynamically decide if to use system xcode 2019-07-29 08:20:24 +00:00
.vpython [tools] Implement confidence-based number of runs 2019-05-09 09:42:28 +00:00
.ycm_extra_conf.py Fix ycm config for headers without source 2019-12-09 11:59:21 +00:00
AUTHORS [builtins][MIPS]: Workaround gas auto-align issue 2020-04-17 09:36:25 +00:00
BUILD.gn [snapshot] Rename the partial-* files to context-* 2020-04-23 12:41:22 +00:00
CODE_OF_CONDUCT.md Explicitly state that the Chromium Code of Conduct also applies to V8 2016-03-02 09:51:24 +00:00
codereview.settings Make Gerrit the default code review for V8 2017-06-30 17:37:37 +00:00
COMMON_OWNERS heap: Add Oilpan folks to COMMON_OWNERS 2020-04-14 08:55:52 +00:00
DEPS Fix autoroller failure 2020-04-21 16:41:53 +00:00
ENG_REVIEW_OWNERS Add eng review owners as escalation path 2019-05-15 19:12:10 +00:00
INFRA_OWNERS Remove myself from owners 2019-12-12 14:22:32 +00:00
INTL_OWNERS Add missing owners files 2019-05-31 07:21:01 +00:00
LICENSE [wasm] Draft version of C/C++ Wasm API 2019-04-17 16:00:26 +00:00
LICENSE.fdlibm Add LICENSE.fdlibm for all the fdlibm imported sources. 2016-06-09 07:17:03 +00:00
LICENSE.strongtalk Add LICENSE.v8, LICENSE.strongtalk and LICENSE.valgrind to the v8 2011-02-03 07:10:06 +00:00
LICENSE.v8 Add LICENSE.v8, LICENSE.strongtalk and LICENSE.valgrind to the v8 2011-02-03 07:10:06 +00:00
LICENSE.valgrind Add LICENSE.v8, LICENSE.strongtalk and LICENSE.valgrind to the v8 2011-02-03 07:10:06 +00:00
MIPS_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
OWNERS Add syg@chromium.org as DEPS owner for test262 rolls 2019-09-17 19:29:11 +00:00
PPC_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
PRESUBMIT.py Remove the #undef check from the Presubmit for .cc files 2020-01-24 15:24:51 +00:00
README.md [docs] Change links from old wiki to v8.dev 2019-03-07 12:13:30 +00:00
S390_OWNERS Move architecture dependent files 2019-05-28 14:02:15 +00:00
WATCHLISTS Stop watching for API changes in WATCHLISTS 2020-04-08 07:06:45 +00:00

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.