[webkit-changes] [WebKit/WebKit] d9e584: [JSC] Create (async) generator object after perfor...

[Commit Queue]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: d9e5846a73b15cd274436a0f8abff8d1c00241fb
      https://github.com/WebKit/WebKit/commit/d9e5846a73b15cd274436a0f8abff8d1c00241fb
  Author: Alexey Shvayka <ashvayka at apple.com>
  Date:   2023-10-26 (Thu, 26 Oct 2023)

  Changed paths:
    A JSTests/stress/regress-263617.js
    M JSTests/test262/expectations.yaml
    M Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp

  Log Message:
  -----------
  [JSC] Create (async) generator object after performing FunctionDeclarationInstantiation
https://bugs.webkit.org/show_bug.cgi?id=263617
<rdar://problem/117439419>

Reviewed by Justin Michaud.

initializeDefaultParameterValuesAndSetupFunctionScopeStack(), which implements steps 25-26 of
FunctionDeclarationInstantiation [1], may call into arbitrary userland code when evaluating
default parameters, affecting the [[Prototype]] of created & returned (async) generator object.

With this change, (async) generator object creation happens after parameter initialization,
aligning JSC with the spec [1][2] and SpiderMonkey.

[1]: https://tc39.es/ecma262/#sec-functiondeclarationinstantiation
[2]: https://tc39.es/ecma262/#sec-runtime-semantics-evaluategeneratorbody (step 2)
[3]: https://tc39.es/ecma262/#sec-runtime-semantics-evaluateasyncgeneratorbody (step 2)

* JSTests/stress/regress-263617.js: Added.
* JSTests/test262/expectations.yaml: Mark 8 tests as passing.
* Source/JavaScriptCore/bytecompiler/BytecodeGenerator.cpp:
(JSC::BytecodeGenerator::BytecodeGenerator):

Canonical link: https://commits.webkit.org/269823@main