cmd/compile/internal/syntax: remove strbyteseql

cmd/compile already optimizes "string(b) == s" to avoid allocating a
temporary string.

Change-Id: I4244fbeae8d350261494135c357f9a6e2ab7ace3
Reviewed-on: https://go-review.googlesource.com/28931
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/cmd/compile/internal/syntax/scanner.go

@@ -317,7 +317,7 @@ func (s *scanner) ident() {
 
 	// possibly a keyword
 	if len(lit) >= 2 {
-		if tok := keywordMap[hash(lit)]; tok != 0 && strbyteseql(tokstrings[tok], lit) {
+		if tok := keywordMap[hash(lit)]; tok != 0 && tokstrings[tok] == string(lit) {
 			s.nlsemi = contains(1<<_Break|1<<_Continue|1<<_Fallthrough|1<<_Return, tok)
 			s.tok = tok
 			return
@@ -347,18 +347,6 @@ func hash(s []byte) uint {
 	return (uint(s[0])<<4 ^ uint(s[1]) + uint(len(s))) & uint(len(keywordMap)-1)
 }
 
-func strbyteseql(s string, b []byte) bool {
-	if len(s) == len(b) {
-		for i, b := range b {
-			if s[i] != b {
-				return false
-			}
-		}
-		return true
-	}
-	return false
-}
-
 var keywordMap [1 << 6]token // size must be power of two
 
 func init() {