cmd/compile: update and reenable Formats test

Change-Id: I9c0da13d21551dbf766156472224370ab9badfe9
Reviewed-on: https://go-review.googlesource.com/28778
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/gc/fmt_test.go

@@ -66,8 +66,6 @@ type CallSite struct {
 }
 
 func TestFormats(t *testing.T) {
-	return // temporarily disabled
-
 	testenv.MustHaveGoBuild(t) // more restrictive than necessary, but that's ok
 
 	// determine .go files
@@ -479,12 +477,33 @@ var formatMapping = map[string]string{
 	"*Field %v":                          "",
 	"*Mpflt %v":                          "",
 	"*Mpint %v":                          "",
+	"*Node %#v":                          "",
+	"*Node %+1v":                         "",
+	"*Node %+v":                          "",
+	"*Node %0j":                          "",
+	"*Node %1v":                          "",
+	"*Node %2v":                          "",
+	"*Node %j":                           "",
 	"*Node %p":                           "",
 	"*Node %s":                           "",
 	"*Node %v":                           "",
+	"*Sym % v":                           "",
+	"*Sym %+v":                           "",
+	"*Sym %-v":                           "",
+	"*Sym %01v":                          "",
+	"*Sym %1v":                           "",
 	"*Sym %p":                            "",
 	"*Sym %s":                            "",
 	"*Sym %v":                            "",
+	"*Type % -v":                         "",
+	"*Type %#v":                          "",
+	"*Type %+v":                          "",
+	"*Type %- v":                         "",
+	"*Type %-1v":                         "",
+	"*Type %-v":                          "",
+	"*Type %01v":                         "",
+	"*Type %1v":                          "",
+	"*Type %2v":                          "",
 	"*Type %p":                           "",
 	"*Type %s":                           "",
 	"*Type %v":                           "",
@@ -505,11 +524,17 @@ var formatMapping = map[string]string{
 	"EType %v":                           "",
 	"Level %d":                           "",
 	"Level %v":                           "",
+	"Nodes %#s":                          "",
+	"Nodes %#v":                          "",
+	"Nodes %+v":                          "",
+	"Nodes %.v":                          "",
 	"Nodes %v":                           "",
 	"Op %#v":                             "",
 	"Op %d":                              "",
 	"Op %s":                              "",
 	"Op %v":                              "",
+	"Val %#v":                            "",
+	"Val %s":                             "",
 	"Val %v":                             "",
 	"[16]byte %x":                        "",
 	"[]*Node %v":                         "",