Rename methods in ResourceFetcher to describe what's done in them correctly

loadRequest() was calling load() before
http://trac.webkit.org/changeset/129462 but no longer calling it. The
same about revalidateResource(). Give them new names describing what's
done in them.

Also, this CL makes some style fix in them.

BUG=none
R=japhet

Review URL: https://codereview.chromium.org/318003002

git-svn-id: svn://svn.chromium.org/blink/trunk@175767 bbb929c8-8fbe-4397-9dbb-9b2b20218538