fix(formatter): normalize ChainExpression with TSNonNullExpression to match Prettier

[Boshen]

Summary

Fixes the formatting of optional chain expressions combined with non-null assertions to match Prettier's output:

• (a?.b!).c now prints as (a?.b)!.c (moves ! outside parentheses)
• (a?.b)!.c correctly preserves parentheses
• (a?.b)![c?.d!] correctly handles computed member access

Implementation

The fix introduces a shared chain_expression_needs_parens function that handles two AST patterns:

1. ChainExpression > TSNonNullExpression - handled in write() by printing inner content with parens, then !
2. TSNonNullExpression > ChainExpression - handled in needs_parentheses() by recursively checking grandparent

This matches Prettier's behavior documented in their clean.js.

Test plan

• All 18 test cases in typescript/non-null/optional-chain.ts now pass
• Additional chain-expression tests now pass
• TS Prettier conformance improved from 95.39% to 96.05%
• All 144 formatter unit tests pass

🤖 Generated with Claude Code

[Copilot]

Pull request overview

This PR fixes the formatting of optional chain expressions combined with non-null assertions to match Prettier's output. The fix handles two AST patterns: ChainExpression > TSNonNullExpression and TSNonNullExpression > ChainExpression.

Changes:

• Extracted chain_expression_needs_parens as a shared function to determine parenthesization needs
• Updated ChainExpression::write() to manually handle parentheses when the child is a TSNonNullExpression, printing (a?.b)! instead of (a?.b!)
• Added recursive case in chain_expression_needs_parens to handle TSNonNullExpression parents by checking the grandparent context

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
tasks/prettier_conformance/snapshots/prettier.ts.snap.md	Updates conformance metrics showing improvement from 95.39% to 96.05%, with 4 previously failing test files now passing
crates/oxc_formatter/src/print/mod.rs	Adds special handling in ChainExpression::write() to reorder non-null assertions outside parentheses
crates/oxc_formatter/src/parentheses/mod.rs	Exports the new chain_expression_needs_parens function
crates/oxc_formatter/src/parentheses/expression.rs	Extracts parenthesization logic into shared function and adds recursive handling for TSNonNullExpression parents

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[codspeed-hq]

Merging this PR will not alter performance

✅ 38 untouched benchmarks
⏩ 7 skipped benchmarks¹

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_{Comparing fix/formatter-chain-expression-non-null (f1e1b25) with main (9b902b6)}

Footnotes

1. 7 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩

[Boshen]

Merge activity

• Jan 16, 11:14 AM UTC: The merge label '0-merge' was detected. This PR will be added to the Graphite merge queue once it meets the requirements.
• Jan 16, 11:14 AM UTC: Boshen added this pull request to the Graphite merge queue.
• Jan 16, 11:26 AM UTC: Merged by the Graphite merge queue.

[fisker]

FYI: I plan to change this to keep AST unchanged.