Prevent font-lock colision in QuasiQuotes

[gracjan]

Do not do double coloring of QuasiQuotes,

[gracjan]

Taken from #1249.

[gracjan]

So font-lock first does syntactic and later keyword fontification;

        (unless font-lock-keywords-only
          (font-lock-fontify-syntactically-region beg end loudly))
        (font-lock-fontify-keywords-region beg end loudly)))))

So the second one overrides the first when there is no face set.

[gracjan]

@mrkkrp, note this issue.