Check the navigation load as well as the Document owner before committing
a javascript URL string result. A form submission or Location navigation
started during script execution must keep its pending request.
Add four Browser integration tests covering 13 scenarios, including GET,
POST, named targets, successor javascript URLs, unrelated frames, and
canceled navigation. Record the newly passing jsurl-form-submit WPT.
Validation: cargo fmt --all; workspace all-targets all-features Clippy
with -D warnings; cargo nextest run --no-fail-fast (17,901 passed,
13 skipped). Focused WPT: 103 cases, one new pass, no regressions.
