[refactor] Remove the AlgorithmRegistry singleton.

The problem with AlgorithmRegistry is that it is not threadsafe.

BUG=357673,245025

Review URL: https://codereview.chromium.org/211423008

git-svn-id: svn://svn.chromium.org/blink/trunk@170672 bbb929c8-8fbe-4397-9dbb-9b2b20218538