cmd/compile: use regular rather than indexed format string

This enables the format test to process this file (the format
test doesn't handle indexed formats, and this is the only place
in the compiler where they occur).

Change-Id: I99743f20c463f181a589b210365f70162227d4e0
Reviewed-on: https://go-review.googlesource.com/28932
Run-TryBot: Robert Griesemer <gri@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>

src/cmd/compile/internal/ssa/html.go

@@ -341,7 +341,8 @@ func (v *Value) HTML() string {
 	// TODO: Using the value ID as the class ignores the fact
 	// that value IDs get recycled and that some values
 	// are transmuted into other values.
-	return fmt.Sprintf("<span class=\"%[1]s ssa-value\">%[1]s</span>", v.String())
+	s := v.String()
+	return fmt.Sprintf("<span class=\"%s ssa-value\">%s</span>", s, s)
 }
 
 func (v *Value) LongHTML() string {
@@ -369,7 +370,8 @@ func (b *Block) HTML() string {
 	// TODO: Using the value ID as the class ignores the fact
 	// that value IDs get recycled and that some values
 	// are transmuted into other values.
-	return fmt.Sprintf("<span class=\"%[1]s ssa-block\">%[1]s</span>", html.EscapeString(b.String()))
+	s := html.EscapeString(b.String())
+	return fmt.Sprintf("<span class=\"%s ssa-block\">%s</span>", s, s)
 }
 
 func (b *Block) LongHTML() string {