Translate CloseEventCodeNotSpecified to 1005

In the new WebSocket implementation in Blink, translate
CloseEventCodeNotSpecified (-1) to CloseEventCodeNoStatusRcvd
(1005). This will make the browser create a Close frame with no payload
after https://codereview.chromium.org/175213002 is landed.

BUG=345683

Review URL: https://codereview.chromium.org/175243002

git-svn-id: svn://svn.chromium.org/blink/trunk@167877 bbb929c8-8fbe-4397-9dbb-9b2b20218538