Change expectations to "Invalid frame header"

The new WebSocket implementation cannot produce detailed error messages
for errors in frame parsing. They are all collapsed to
ERR_WS_PROTOCOL_ERROR, which translates to "Invalid frame header".

This CL updates the affected layout tests to use the new message:

invalid-encode-length.html
long-control-frame.html
too-long-payload.html

Also re-enable the tests in TestExpections.

BUG=339373

Review URL: https://codereview.chromium.org/179533005

git-svn-id: svn://svn.chromium.org/blink/trunk@167992 bbb929c8-8fbe-4397-9dbb-9b2b20218538