Update test main template to match current version in Go 1.8.

See golang/go@c56cc9b?w=1.

Fixes the following issue when running gopherjs test:

	_testmain.go:162:25: cannot use matchString (value of type func(pat string, str string) (result bool, err error)) as testing.testDeps value in argument to testing.MainStart: missing method MatchString

tool.go

@@ -919,8 +919,8 @@ import (
 {{if not .TestMain}}
 	"os"
 {{end}}
-	"regexp"
 	"testing"
+	"testing/internal/testdeps"
 
 {{if .ImportTest}}
 	{{if .NeedTest}}_test{{else}}_{{end}} {{.Package.ImportPath | printf "%q"}}
@@ -948,22 +948,8 @@ var examples = []testing.InternalExample{
 {{end}}
 }
 
-var matchPat string
-var matchRe *regexp.Regexp
-
-func matchString(pat, str string) (result bool, err error) {
-	if matchRe == nil || matchPat != pat {
-		matchPat = pat
-		matchRe, err = regexp.Compile(matchPat)
-		if err != nil {
-			return
-		}
-	}
-	return matchRe.MatchString(str), nil
-}
-
 func main() {
-	m := testing.MainStart(matchString, tests, benchmarks, examples)
+	m := testing.MainStart(testdeps.TestDeps{}, tests, benchmarks, examples)
 {{with .TestMain}}
 	{{.Package}}.{{.Name}}(m)
 {{else}}