internal/span: span to protocol needs position as well as offset

Change-Id: I4f39abb5932a951b2e5fa0932f478b00138e626a
Reviewed-on: https://go-review.googlesource.com/c/tools/+/170186
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/internal/lsp/protocol/span.go b/internal/lsp/protocol/span.go
index 998856f..d4d841d 100644
--- a/internal/lsp/protocol/span.go
+++ b/internal/lsp/protocol/span.go
@@ -43,7 +43,7 @@
 	if m.URI != s.URI() {
 		return Range{}, fmt.Errorf("column mapper is for file %q instead of %q", m.URI, s.URI())
 	}
-	s, err := s.WithOffset(m.Converter)
+	s, err := s.WithAll(m.Converter)
 	if err != nil {
 		return Range{}, err
 	}