fix(object/ module/): convert remaining panics to EngineError::Panic

[KaustubhOG]

Part of #3241. Follow-up to #5063 addressing review comment.

Changes:

• operations.rs: converted 5 panics — ToObject, CreateDataPropertyOrThrow (js_expect), private_field_add, private_method_or_accessor_add, private_set (try_borrow_mut)
• internal_methods/mod.rs: migrated 6 borrow call sites to try_borrow/try_borrow_mut
• internal_methods/string.rs: migrated 3 borrow call sites, return type of string_get_own_property changed to JsResult<Option>
• builtins/jsdataview.rs: migrated 2 borrow call sites to try_borrow

[KaustubhOG]

@jedel1043 Following up on your review in #5063 regarding the borrow()/borrow_mut() guards in jsobject.rs (lines 820, 850).

Changing their return types from Ref<'_, Object<T>>/RefMut<'_, Object<T>> to JsResult<...> would cascade into hundreds of call sites across object/, shape/, and internal_methods/. Two possible approaches:

1. Change the foundation methods themselves and update all call sites
2. Leave the foundation methods as-is and only convert specific call sites inside JsResult-returning functions to use try_borrow + js_expect directly

does thiss idea looks fine ?

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	53,125	53,125	0
Passed	51,049	51,049	0
Ignored	1,482	1,482	0
Failed	594	594	0
Panics	0	0	0
Conformance	96.09%	96.09%	0.00%

Tested main commit: d6d76d86e9e18fca07f318f1db434cc8abffaf14
Tested PR commit: ab5705d887e525fd5aa4e066f0abd1623b4c8d20
Compare commits: d6d76d8...ab5705d

[jedel1043]

Changing their return types from Ref<', Object>/RefMut<', Object> to JsResult<...> would cascade into hundreds of call sites across object/, shape/, and internal_methods/.

I was more thinking of a progressive migration to try_borrow and try_borrow_mut, leaving the panicking methods there. Users would still wanna panic sometimes, so having that API in place is still useful.

[codecov]

Codecov Report

❌ Patch coverage is 56.25000% with 21 lines in your changes missing coverage. Please review.
✅ Project coverage is 59.77%. Comparing base (6ddc2b4) to head (ab5705d).
⚠️ Report is 947 commits behind head on main.

Files with missing lines	Patch %	Lines
core/engine/src/object/internal_methods/string.rs	25.00%	12 Missing ⚠️
core/engine/src/object/builtins/jsdataview.rs	0.00%	5 Missing ⚠️
core/engine/src/object/operations.rs	50.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5311       +/-   ##
===========================================
+ Coverage   47.24%   59.77%   +12.52%     
===========================================
  Files         476      589      +113     
  Lines       46892    63690    +16798     
===========================================
+ Hits        22154    38069    +15915     
- Misses      24738    25621      +883     

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[KaustubhOG]

Changing their return types from Ref<', Object>/RefMut<', Object> to JsResult<...> would cascade into hundreds of call sites across object/, shape/, and internal_methods/.

I was more thinking of a progressive migration to try_borrow and try_borrow_mut, leaving the panicking methods there. Users would still wanna panic sometimes, so having that API in place is still useful.

Ok. Will migrate call sites inside JsResult-returning functions across object/ to use try_borrow/try_borrow_mut directly, leaving the panicking foundation methods in place. Will update this PR shortly.

[KaustubhOG]

@jedel1043 Updated. Migrated all eligible borrow/borrow_mut call sites inside JsResult-returning functions across object/ to use try_borrow/try_borrow_mut directly.

Remaining .borrow()/.borrow_mut() calls in object/ are either in non-JsResult contexts (bool, Option, () returns), test blocks, or the foundation borrow()/borrow_mut() methods themselves ,all left as-is per suggestion.