The current logic for a cors cache match does not consider "credentials
is false and request's credentials mode is not "include" or credentials
is true."
implements data-url fetching
Fixes#10165
jdm mentioned of decoupling the, payload loading mechanism to data_loader.rs. So accordingly a `decoder` method has been added to data_loader.
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When fetching about:blank, response body should be the empty byte
sequence.
Spec: https://fetch.spec.whatwg.org/#concept-basic-fetch
Before this change, response body would be set to `ResponseBody::Empty`,
and then fetching would result in an infinite loop at step 19 in fn
`main_fetch` (methods.rs).
In function Request::fetch_main, flag local_urls_only (if set)
should allow fetching local urls only. Before this change, the flag had
the inverse behaviour.
