html: update quotes about the list of active formatting elements
html: update quotes about the list of active formatting elements

See https://html.spec.whatwg.org/multipage/parsing.html#the-list-of-active-formatting-elements

Updates golang/go#23071

Change-Id: I015c394ed34d721e9e4a4d3e797d06d750c1864e
Reviewed-on: https://go-review.googlesource.com/94837
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

golang/net