Compact has been inconsistently escaping only some problematic characters
(U+2028 and U+2029), but not others (<, > and &). This change addresses
this inconsistency by removing the escaping of U+2028 and U+2029.

Callers who need to escape the output of Compact should use HTMLEscape
which escapes <, >, &, U+2028 and U+2029.

Fixes #34070
Fixes #30357
Updates #5836

Change-Id: Icfce7691d2b8b1d9b05ba7b64d2d1e4f3b67871b
GitHub-Last-Rev: 38859fe3e2fd586bbd45175c2742f7b123836bf3
GitHub-Pull-Request: golang/go#34804
Reviewed-on: https://go-review.googlesource.com/c/go/+/200217Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Run-TryBot: Daniel Martí <mvdan@mvdan.cc>
TryBot-Result: Gobot Gobot <gobot@golang.org>