text/template/parse: don't show itemType in error messages

so that the user don't need to decipher something like this:
template: main:1: expected %!s(parse.itemType=14) in end; got "|"
now they get this:
template: main:1: unexpected "|" in end

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/7128054

src/pkg/text/template/parse/parse.go

@@ -151,7 +151,7 @@ func (t *Tree) error(err error) {
 func (t *Tree) expect(expected itemType, context string) item {
 	token := t.nextNonSpace()
 	if token.typ != expected {
-		t.errorf("expected %s in %s; got %s", expected, context, token)
+		t.unexpected(token, context)
 	}
 	return token
 }
@@ -160,7 +160,7 @@ func (t *Tree) expect(expected itemType, context string) item {
 func (t *Tree) expectOneOf(expected1, expected2 itemType, context string) item {
 	token := t.nextNonSpace()
 	if token.typ != expected1 && token.typ != expected2 {
-		t.errorf("expected %s or %s in %s; got %s", expected1, expected2, context, token)
+		t.unexpected(token, context)
 	}
 	return token
 }