chore: fix Locator type issues

[mxschmitt]

This fixes

Type 'Locator' is missing the following properties from type 'Locator': _frame, _selector, _withElement, _equals, and 4 more.

Broken since 7aac96d

This issue was that protocol types and api types diverged. Once accepted value to be nullable (protocol) the other one didn't accept it. Why the linting error doesn't get surfaced in our normal CI status checks is a mystery. We could now also revert #34682.

[github-actions]

Test results for "tests 1"

1 failed
❌ [webkit-library] › tests/library/inspector/title.spec.ts:35:5 › should update primary page URL when original primary closes @webkit-ubuntu-22.04-node18

12 flaky

⚠️ [firefox-page] › tests/page/page-evaluate.spec.ts:403:3 › should throw for too deep reference chain @firefox-ubuntu-22.04-node18
⚠️ [chromium-library] › tests/library/video.spec.ts:379:5 › screencast › should capture navigation @ubuntu-20.04-chromium-tip-of-tree
⚠️ [playwright-test] › tests/ui-mode-trace.spec.ts:341:5 › should work behind reverse proxy @ubuntu-latest-node22-1
⚠️ [webkit-library] › tests/library/browsercontext-reuse.spec.ts:50:1 › should reset serviceworker @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/inspector/cli-codegen-1.spec.ts:55:7 › cli codegen › should double click @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/trace-viewer.spec.ts:149:1 › should open simple trace viewer @webkit-ubuntu-22.04-node18
⚠️ [webkit-library] › tests/library/trace-viewer.spec.ts:1298:1 › should pick locator in iframe @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-leaks.spec.ts:82:5 › click should not leak @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-leaks.spec.ts:107:5 › fill should not leak @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-leaks.spec.ts:161:5 › waitFor should not leak @webkit-ubuntu-22.04-node18
⚠️ [webkit-page] › tests/page/page-set-input-files.spec.ts:205:3 › should upload multiple large files @webkit-ubuntu-22.04-node18
⚠️ [playwright-test] › tests/ui-mode-test-watch.spec.ts:145:5 › should watch all @windows-latest-node18-1

37822 passed, 654 skipped
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Merge workflow run.