text/template: revert minor change to Name method

For  better printing, I recently changed Name to return "<unnamed>" for templates
with empty names, but this causes trouble for the many packages that used "" as
the template name, so restore the old behavior.
It's usually printed as a quoted string anyway, so it should be fine.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/7577044

src/pkg/text/template/template.go

@@ -40,9 +40,6 @@ func New(name string) *Template {
 
 // Name returns the name of the template.
 func (t *Template) Name() string {
-	if t.name == "" {
-		return "<unnamed>"
-	}
 	return t.name
 }