Fix issue 12495: Infinite loop in ToolStripItemCollection.AddRange

[Olina-Zhang]

Fixes #12495 and #4454

Proposed changes

• Early return for empty collection
• Converts the ToolStripItemCollection into a temporary array (using ToArray()) to avoid modifying the original collection during iteration. This ensures that items can be safely added to the new collection without causing exceptions or unintended behavior, especially when items are removed from the original collection if they have a different owner control.
• Add unit test for issue Infinite loop in ToolStripItemCollection.AddRange #12495 case

Regression?

• Yes

Test methodology

• Test fixing for GH issues: 12495 and 4454 manually
• Unit test

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.73237%. Comparing base (af49f16) to head (2f4c086).
Report is 23 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #12513         +/-   ##
===================================================
- Coverage   75.73242%   75.73237%   -0.00006%     
===================================================
  Files           3153        3157          +4     
  Lines         635807      636123        +316     
  Branches       46975       47004         +29     
===================================================
+ Hits          481512      481751        +239     
- Misses        150870      150900         +30     
- Partials        3425        3472         +47     

Flag	Coverage Δ
Debug	75.73237% <100.00000%> (-0.00006%)	⬇️
integration	18.16407% <0.00000%> (-0.09047%)	⬇️
production	49.28844% <100.00000%> (-0.01708%)	⬇️
test	97.04462% <100.00000%> (-0.00532%)	⬇️
unit	46.52041% <100.00000%> (+0.25733%)	⬆️

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[Tanya-Solyanik]

Looks good, added minor comments in additions to Leaf's one

[LeafShi1]

LGTM