fix eval delete bindings

[Monti-27]

Fixes #5333.

Direct eval-created local var and function bindings were not treated as deletable at runtime, so delete left them visible and later var initialization could recreate them.

This tracks deleted eval-created local bindings in function environments and avoids recreating them after deletion.

Tests:

• cargo test -p boa_engine env -- --nocapture
• cargo test -p boa_engine unary_delete -- --nocapture
• cargo clippy -p boa_engine --all-features --all-targets -- -D warnings
• cargo make run-ci

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	53,125	53,125	0
Passed	51,051	51,054	+3
Ignored	1,482	1,482	0
Failed	592	589	-3
Panics	0	0	0
Conformance	96.10%	96.10%	+0.01%

Fixed tests (4):

test/staging/sm/expressions/nested-delete-name-in-evalcode.js (previously Failed)
test/staging/sm/extensions/nested-delete-name-in-evalcode.js (previously Failed)
test/language/eval-code/direct/var-env-func-init-local-new-delete.js (previously Failed)
test/language/eval-code/direct/var-env-var-init-local-new-delete.js (previously Failed)

Broken tests (1):

test/staging/sm/regress/regress-643222.js (previously Passed)

Tested main commit: 3ee2b71a306334c2b2a0dcc20ac4b5e1c5a71558
Tested PR commit: 10f36a05738bac57c412fec069b9e0d817d6dad0
Compare commits: 3ee2b71...10f36a0

[codecov]

Codecov Report

❌ Patch coverage is 94.11765% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.91%. Comparing base (6ddc2b4) to head (10f36a0).
⚠️ Report is 957 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/environments/runtime/mod.rs	89.65%	3 Missing ⚠️
...e/src/environments/runtime/declarative/function.rs	95.83%	1 Missing ⚠️
...engine/src/environments/runtime/declarative/mod.rs	93.33%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5344       +/-   ##
===========================================
+ Coverage   47.24%   59.91%   +12.67%     
===========================================
  Files         476      590      +114     
  Lines       46892    63803    +16911     
===========================================
+ Hits        22154    38228    +16074     
- Misses      24738    25575      +837     

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[zhuzhu81998]

i am not familiar with this part of the codebase, but this feels, kinda hacky?

are you sure this is not something that happens because of incompliance with spec somewhere?

[Monti-27]

i am not familiar with this part of the codebase, but this feels, kinda hacky?

are you sure this is not something that happens because of incompliance with spec somewhere?

Yeah, fair point. the current approach is not clean enough. The Test262 report also caught a regression around eval("var x=delete(x)") so I’ll rework this instead of trying to patch around it