fail fast utf-8 aka 6.4.* autobahn
I see the benefit that could bring but fail to understand how the test working specificaly 6.4.2.
6.4.2 work on same level as 6.4.1 as frame.

6.4.1 consist of 2 frame ( last frame didn't count 

> 1 - \xce\xba\xe1\xbd\xb9\xcf\x83\xce\xbc\xce\xb5  ( UTF8 = true )
> 2 - \xf4\x90\x80\x80 ( UTF-8 = false )
> --- fail fast
> 3- \x65\x64\x69\x74\x65\x64

6.4.2 consist of 

> 1- \xce\xba\xe1\xbd\xb9\xcf\x83\xce\xbc\xce\xb5\xf4 ( UTF-8 false )
> ---fail fast
> 2- \x90
> 3- \x80\x80\x65\x64\x69\x74\x65\x64

Did you manage to make those test pass ? Seem it fail too fast but first frame of 6.4.2 are not UTF8 or I'm wrong.
