cmd/cover: remove unused global var and the unquote function

Change-Id: I52a39f2d8f1a296f23624e3ec577d9ad1b8302f1
Reviewed-on: https://go-review.googlesource.com/126555
Run-TryBot: Yury Smolsky <yury@smolsky.by>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alan Donovan <adonovan@google.com>

src/cmd/cover/cover.go

@@ -16,7 +16,6 @@ import (
 	"log"
 	"os"
 	"sort"
-	"strconv"
 
 	"cmd/internal/edit"
 	"cmd/internal/objabi"
@@ -294,17 +293,6 @@ func (f *File) Visit(node ast.Node) ast.Visitor {
 	return f
 }
 
-// unquote returns the unquoted string.
-func unquote(s string) string {
-	t, err := strconv.Unquote(s)
-	if err != nil {
-		log.Fatalf("cover: improperly quoted string %q\n", s)
-	}
-	return t
-}
-
-var slashslash = []byte("//")
-
 func annotate(name string) {
 	fset := token.NewFileSet()
 	content, err := ioutil.ReadFile(name)