Update WebKit commit to aa4997abc9126f5a7557c9ecb7e8104779d87ec4

[robobun]

Summary

• Updates WebKit commit from 684d4551ce5f62683476409d7402424e0f6eafb5 to aa4997abc9126f5a7557c9ecb7e8104779d87ec4
• Build completed successfully with no errors
• Verified functionality with hello world test

Test plan

• Build completed successfully
• Hello world test passes with bun bd
• No build errors encountered

🤖 Generated with Claude Code

[robobun]

^{Updated 8:55 PM PT - Aug 14th, 2025}

❌ Your commit 315a1bed has 7 failures in Build #23016:

• test/js/bun/shell/shell-load.test.ts - 1 failing on 🍎 14 aarch64
• test/js/node/test/parallel/test-worker-memory.js - code 1 on 🍎 14 aarch64
• test/js/node/test/parallel/test-gc-http-client-connaborted.js - timeout on 🐧 3.21 x64-baseline
• test/js/node/worker_threads/worker_threads.test.ts - pid 28775 segmentation fault on 🐧 25.04 aarch64
• test/js/node/test/parallel/test-child-process-fork-exec-path.js - timeout on 🐧 12 x64-asan
• test/js/node/test/parallel/test-child-process-spawnsync-shell.js - timeout on 🪟 2019 x64-baseline
• test/js/node/test/parallel/test-child-process-spawnsync-shell.js - timeout on 🪟 2019 x64
• test/js/bun/shell/pipeline_stack.test.ts - 1 failing on 🪟 2019 x64
• test/js/bun/shell/pipeline_stack.test.ts - 1 failing on 🪟 2019 x64-baseline

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🧪   To try this PR locally:

bunx bun-pr 21878

That installs a local version of the PR into your bun-21878 executable, so you can run:

bun-21878 --bun