Rename a few Member and Persistent methods to make the transition
period simpler.

We will need to have Members and Persistents instead of RefPtrs.
On RefPtrs the methods that correspond to raw and clear are called
get and release. Unify on the RefPtr methods to make the transition
period code simpler.

Fix comparison operators that were unused and did not work because
they accessed private members.

R=haraken@chromium.org, wibling@chromium.org, zerny@chromium.org, erik.corry@gmail.com
BUG=

Review URL: https://codereview.chromium.org/138203002

git-svn-id: svn://svn.chromium.org/blink/trunk@165110 bbb929c8-8fbe-4397-9dbb-9b2b20218538