internal/runtime/gc/scan: correct size class size check
This check intends to skip size classes that are too big for scanSpan,
but it compares the size class index with a byte size. It must do the
conversion first.
For #73581.
Change-Id: I6a6a636c8d19fa3bf2a2b609870d67d33f47f66e
Reviewed-on: https://go-review.googlesource.com/c/go/+/715460
Auto-Submit: Michael Pratt <mpratt@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Knyszek <mknyszek@google.com>