Do not revalidate when ResourceLoaderOptions.synchronousPolicy is different

This CL adds a check of synchronousPolicy to
ResourceLoaderOptions::canReuseRequest() to avoid Resources to be reused
between sync and async requests.
This CL also removes a condition from
ResourceFetcher::determineRevalidationPolicy() that is covered by the newly
added check.

CachingCorrectnessTest is updated so that it doesn't use synchronous
RawResource requests.


Cr-Commit-Position: refs/heads/master@{#422725}
8 files changed