cmd/pprof/internal/profile: ignore comments when parsing heap profiles

Fixes #10659.

Change-Id: I22dc306ce6f398dd40010ac430928a718d67d466
Reviewed-on: https://go-review.googlesource.com/9623Reviewed-by: Russ Cox <rsc@golang.org>

src/cmd/pprof/internal/profile/legacy_profile.go

@@ -554,9 +554,10 @@ func parseHeap(b []byte) (p *Profile, err error) {
 			}
 		}
 
-		if l = strings.TrimSpace(l); l == "" {
+		if isSpaceOrComment(l) {
 			continue
 		}
+		l = strings.TrimSpace(l)
 
 		if sectionTrigger(l) != unrecognizedSection {
 			break