chore(bidi): add support for browser.setDownloadBehavior

[hbenl]

Fixes the following tests in Firefox:

• library/download.spec.ts:
  • "download event > should report download when navigation turns into download"
  • "download event > should work with Cross-Origin-Opener-Policy"
  • "download event > should report downloads with acceptDownloads: false"
  • "download event > should report downloads with acceptDownloads: true"
  • "download event > should report downloads for download attribute"
  • "download event > should save to user-specified path without updating original path"
  • "download event > should save to two different paths with multiple saveAs calls"
  • "download event > should save to overwritten filepath"
  • "download event > should create subdirectories when saving to non-existent user-specified path"
  • "download event > should report non-navigation downloads"
  • "download event > should report download path within page.on('download', …) handler for Files"
  • "download event > should delete file"
  • "download event > should expose stream"
  • "download event > should delete downloads on context destruction"
  • "download event > should delete downloads on browser gone"
  • "download event > should download large binary.zip"
  • "download event > should not fail explicitly to cancel a download even if that is already finished"
  • "download event > should report downloads with interception"
  • "download event > should emit download event from nested iframes"
  • "should be able to download a PDF file"
  • "should be able to download a inline PDF file via response interception"
  • "should save to user-specified path"
  • "should download successfully when routing"
• library/downloads-path.spec.ts:
  • "downloads path > should keep downloadsPath folder"
  • "downloads path > should delete downloads when context closes"
  • "downloads path > should accept downloads in persistent context"
  • "downloads path > should delete downloads when persistent context closes"
• library/defaultbrowsercontext-1.spec.ts:
  • "should support acceptDownloads option"

[github-actions]

Test results for "tests 1"

1 failed
❌ [playwright-test] › ui-mode-test-network-tab.spec.ts:371 › should not preserve selection across test runs @macos-latest-node20

6 flaky

⚠️ [chromium-library] › library/popup.spec.ts:258 › should not throw when click closes popup `@chromium-ubuntu-22.04-node24`
⚠️ [chromium-page] › page/page-history.spec.ts:95 › goBack/goForward should work with bfcache-able pages `@chromium-ubuntu-22.04-node24`
⚠️ [firefox-library] › library/inspector/cli-codegen-1.spec.ts:1082 › cli codegen › should not throw csp directive violation errors `@firefox-ubuntu-22.04-node20`
⚠️ [playwright-test] › ui-mode-trace.spec.ts:384 › should reveal errors in the sourcetab `@macos-latest-node20`
⚠️ [playwright-test] › ui-mode-trace.spec.ts:812 › should update state on subsequent run `@macos-latest-node20`
⚠️ [playwright-test] › ui-mode-trace.spec.ts:812 › should update state on subsequent run `@windows-latest-node20`

38565 passed, 843 skipped

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Merge workflow run.

[hbenl]

Note that I added the test "should throw if browser dies" to the expectations file because of an issue with the current implementation of browser.setDownloadBehavior in Firefox, see https://bugzilla.mozilla.org/show_bug.cgi?id=2017252#c1.

[github-actions]

Test results for "MCP"

1 failed
❌ [msedge] › mcp/roots.spec.ts:47 › check that trace is saved in workspace @mcp-windows-latest

4882 passed, 135 skipped

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Merge workflow run.