Add WebSerializedOrigin to represent a serialized Web Origin.

Use it in WebSocket.

BUG=339373
R=tyoshino, abarth

Review URL: https://codereview.chromium.org/201593002

git-svn-id: svn://svn.chromium.org/blink/trunk@169591 bbb929c8-8fbe-4397-9dbb-9b2b20218538