Use the standard first-byte analysis for the DFA too.
Use the standard first-byte analysis for the DFA too.

Change-Id: I1b773ac456091b6e9e25d016119829daabc910b0
Reviewed-on: https://code-review.googlesource.com/27270
Reviewed-by: Paul Wankadia <62d4e38bb1380f055ec4b899baa75e52af09c5f7@google.com>

google/re2,google/re2,google/re2,google/re2,google/re2