test: add edge case coverage for Array.prototype.map

[ParthMozarkar]

I added test cases for Array.prototype.map covering some important
edge cases that weren't tested before:

• Empty array
• Callback returning undefined
• Sparse array (holes should be preserved)
• Identity mapping

No existing tests were removed or modified.

Raising this as a draft for review — let me know if any changes
are needed!

[hansl]

We don't need to do all Array functions. Test262 are doing every function in the spec and all edge cases already.

[github-actions]

Test262 conformance changes

Test result	main count	PR count	difference
Total	52,963	52,963	0
Passed	50,545	50,545	0
Ignored	1,426	1,426	0
Failed	992	992	0
Panics	2	2	0
Conformance	95.43%	95.43%	0.00%

Tested main commit: 66a1cd268ce6006918032b5d0f98d3a63c81b188
Tested PR commit: 637541e28725745ff3626eba2f8d955a00deef37
Compare commits: 66a1cd2...637541e

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 59.79%. Comparing base (6ddc2b4) to head (637541e).
⚠️ Report is 916 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #5220       +/-   ##
===========================================
+ Coverage   47.24%   59.79%   +12.55%     
===========================================
  Files         476      582      +106     
  Lines       46892    63460    +16568     
===========================================
+ Hits        22154    37948    +15794     
- Misses      24738    25512      +774     

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[ParthMozarkar]

We don't need to do all Array functions. Test262 are doing every function in the spec and all edge cases already.

Thanks for the approval and the feedback! Understood I won't add
more Array test PRs since test262 already covers those. I'll focus
on more meaningful contributions going forward!