strings: unindent Fields

CL 56470 unindented bytes.Fields, but not strings.Fields. Do so now to
make it easier to diff the two functions for potential differences.

Change-Id: Ifef81f50cee64e8277e91efa5ec5521d8d21d3bd
Reviewed-on: https://go-review.googlesource.com/c/go/+/170951
Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com>
Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/strings/strings.go

@@ -341,7 +341,11 @@ func Fields(s string) []string {
 		wasSpace = isSpace
 	}
 
-	if setBits < utf8.RuneSelf { // ASCII fast path
+	if setBits >= utf8.RuneSelf {
+		// Some runes in the input string are not ASCII.
+		return FieldsFunc(s, unicode.IsSpace)
+	}
+	// ASCII fast path
 	a := make([]string, n)
 	na := 0
 	fieldStart := 0
@@ -369,10 +373,6 @@ func Fields(s string) []string {
 		a[na] = s[fieldStart:]
 	}
 	return a
-	}
-
-	// Some runes in the input string are not ASCII.
-	return FieldsFunc(s, unicode.IsSpace)
 }
 
 // FieldsFunc splits the string s at each run of Unicode code points c satisfying f(c)