Update token binding code to latest drafts

- TBPROTO was updated from -06 to -08; no technical changes (this is the
  version number that is sent over the wire for negotiation). In -04, the
  EC Point format for public key was clarified; this CL also fixes that
  format change.
- TBNEGO was updated from -02 to -03; no technical changes.
- HTTPSTB was updated from -03 to -05; the header name sent by the
  server signaling that the client should reveal the Token Binding ID
  used with the referrer.

BUG=

Review-Url: https://codereview.chromium.org/2137193002
Cr-Original-Commit-Position: refs/heads/master@{#405372}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: 86f0be236649242ee6bd977a66fe06072a765252
1 file changed