Cleanup: Remove the WebCryptoAlgorithm::name() attribute.

This wasn't needed on the embedder's side so may as well remove it from the public API and save a word. (it was also awkward having to pass this in when constructing a WebCryptoAlgorithm)

BUG=245025

Review URL: https://chromiumcodereview.appspot.com/23503016

git-svn-id: svn://svn.chromium.org/blink/trunk@157016 bbb929c8-8fbe-4397-9dbb-9b2b20218538