ref: simplify node occurrence check in validationImpossibleOneway

[dipanshurdev]

Description

Optimize node occurrence detection in impossible oneway validation

Improves code efficiency and readability by replacing a manual loop
with native Array methods. The function now uses indexOf/lastIndexOf
comparison to detect duplicate nodes in a way.

Type of Change

• Performance optimization
• Code quality improvement
• Bug fix
• New feature

Changes

• Replaced manual loop iteration with indexOf() and lastIndexOf() comparison
• Reduced from 7 lines to 1 line
• More idiomatic JavaScript using native array methods
• No behavioral changes - same validation logic

Performance Impact

• Single algorithm pass instead of iterating array
• Leverages optimized native browser/runtime methods
• Reduces memory allocation (no counter variable)

Testing

• No functional changes - same validation behavior
• Detects duplicate nodes the same way
• Code is clearer and more maintainable