regexp: remove dead code

Wasn't convenient enough.

Change-Id: I78270dc22cdb2e264641148e50029a9e4de953cd
Reviewed-on: https://go-review.googlesource.com/30251
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Lance Taylor <iant@golang.org>

src/regexp/onepass.go

@@ -287,11 +287,6 @@ func (p runeSlice) Len() int           { return len(p) }
 func (p runeSlice) Less(i, j int) bool { return p[i] < p[j] }
 func (p runeSlice) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
 
-// Sort is a convenience method.
-func (p runeSlice) Sort() {
-	sort.Sort(p)
-}
-
 var anyRuneNotNL = []rune{0, '\n' - 1, '\n' + 1, unicode.MaxRune}
 var anyRune = []rune{0, unicode.MaxRune}