perf: elide function environment when only this escapes into arrows

[hansl]

When a non-arrow function's sole reason for needing a DeclarativeEnvironment with FunctionSlots is that this escapes into inner arrow functions, skip the Gc environment allocation entirely. Instead, resolve this at arrow-creation time and store it directly on the arrow's OrdinaryFunction via a new SetArrowLexicalThis opcode.

Also includes follow-up fixes for the linked-list EnvironmentStack: promote inline environments before cloning in eval, generator suspend, JSON parse, module execution, and environment binding ops.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	49,902	49,902	0
Ignored	2,222	2,222	0
Failed	839	839	0
Panics	0	0	0
Conformance	94.22%	94.22%	0.00%

Tested main commit: 7eb60775351e9335fe13e457f398a879113ba759
Tested PR commit: 4652b2fb10994af68ab624c5bc41f1525216cad9
Compare commits: 7eb6077...4652b2f

[codecov]

Codecov Report

❌ Patch coverage is 64.63654% with 180 lines in your changes missing coverage. Please review.
✅ Project coverage is 58.70%. Comparing base (6ddc2b4) to head (4652b2f).
⚠️ Report is 882 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/environments/runtime/mod.rs	66.03%	143 Missing ⚠️
core/engine/src/vm/opcode/set/name.rs	0.00%	10 Missing ⚠️
core/engine/src/vm/opcode/get/function.rs	0.00%	9 Missing ⚠️
core/engine/src/bytecompiler/mod.rs	37.50%	5 Missing ⚠️
core/engine/src/builtins/function/mod.rs	50.00%	4 Missing ⚠️
core/engine/src/bytecompiler/function.rs	70.00%	3 Missing ⚠️
core/engine/src/vm/code_block.rs	57.14%	3 Missing ⚠️
core/ast/src/scope.rs	66.66%	1 Missing ⚠️
core/ast/src/scope_analyzer.rs	87.50%	1 Missing ⚠️
core/engine/src/vm/flowgraph/mod.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5019       +/-   ##
===========================================
+ Coverage   47.24%   58.70%   +11.46%     
===========================================
  Files         476      559       +83     
  Lines       46892    61765    +14873     
===========================================
+ Hits        22154    36261    +14107     
- Misses      24738    25504      +766     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.