http2: [compat api] use `Object.create(null)` for `getHeaders`
refactor getHeaders
to initialize headers using
Object.create(null)
Refs: https://github.com/nodejs/node/issues/29829
fixup: lint
Checklist
-
make -j4 test
(UNIX), orvcbuild test
(Windows) passes -
tests and/or benchmarks are included -
documentation is changed or added -
commit message follows commit guidelines