go/parser: correct comment in expectedErrors

If `here` were already the start of the comment, then
the `pos = here` assignment would be redundant. Since pos
is already the start of the comment.

Change-Id: I793334988951ae5441327cb62d7524b423155b74
Reviewed-on: https://go-review.googlesource.com/c/go/+/693295
Reviewed-by: Alan Donovan <[email protected]>
Commit-Queue: Alan Donovan <[email protected]>
Reviewed-by: Robert Findley <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Auto-Submit: Alan Donovan <[email protected]>

Author: mateusz834

src/go/parser/error_test.go

@@ -88,7 +88,7 @@ func expectedErrors(fset *token.FileSet, filename string, src []byte) map[token.
 			s := errRx.FindStringSubmatch(lit)
 			if len(s) == 3 {
 				if s[1] == "HERE" {
-					pos = here // start of comment
+					pos = here // position right after the previous token prior to comment
 				} else if s[1] == "AFTER" {
 					pos += token.Pos(len(lit)) // end of comment
 				} else {