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Part of the removal of PassRefPtr.

Replaces many of the calls to RefPtr::release with a std::move wrap,
which returns a RefPtr instead of a PassRefPtr. As the code currently
stands, most methods still expect a PassRefPtr and so the PassRefPtr
initialising constructor will be called passing in the RefPtr rvalue,
which calls RefPtr::release anyway.

Future patches will see these variables changed from PassRefPtr to
RefPtr type then RefPtr::release will not be used at all.

Does not handle RefPtr::release of non member variables in return
statements as these cases sometimes default to move (in the case of
returning a local variable). These will be handled in future patches.

BUG=494719

Review-Url: https://codereview.chromium.org/2628773002
Cr-Commit-Position: refs/heads/master@{#443416}