fix: allow matching against about:blank and other custom URLs

[agg23]

Fixes #36162.

The JavaScript URL constructor uses any non-scheme colon to indicate the URL hostname, such as with about:blank. This was regressed in #34923, which hides the current value of the URL "path" from the URL constructor. Add a specific check for this case.

This will require similar handling in the ports.

[github-actions]

Test results for "tests 1"

4 flaky

⚠️ [firefox-library] › library/inspector/cli-codegen-1.spec.ts:986:7 › cli codegen › should not throw csp directive violation errors @firefox-ubuntu-22.04-node18
⚠️ [firefox-page] › page/page-wait-for-function.spec.ts:104:3 › should work with strict CSP policy @firefox-ubuntu-22.04-node18
⚠️ [webkit-library] › library/trace-viewer.spec.ts:784:1 › should handle src=blob @webkit-ubuntu-22.04-node18
⚠️ [playwright-test] › ui-mode-test-watch.spec.ts:145:5 › should watch all @windows-latest-node18-1

39302 passed, 818 skipped
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Merge workflow run.