I think this document needs an update. According to the Help Center of SQL Developer version 3.2 (3.2.09) the following SQL*Plus statements are supported in SQL Worksheet:

/
acc[ept]
autotrace
clear screen
conn[ect]
def[ine]
desc[ribe]
doc[ument]
echo
errors
esc[ape]
exec[ute]
exit
feed[back]
help
ho[st]
pagesize
pau[se]
print
pro[mpt]
quit
rem[ark]
roll[back]
set pau[se] {ON | OFF}
sta[rt]
spo[ol]
term[out]
timi[ng]
undef[ine]
user
var[iable]
ver[ify]
whenever
xquery

The following SQL*Plus statements are not supported by the SQL Worksheet:

a[ppend]
archive
attr[ibute]
bre[ak]
bti[tle]
c[hange]
col[umn]
comp[ute]
copy
del
disc[onnect]
ed[it]
get
i[nput]
l[ist]
newpage
oradebug
passw[ord]
r[un]
recover
repf[ooter]
reph[eader]
sav[e]
startup
sho[w]
shu[tdown]
spo[ol]
startup
store
tti[tle]

Kind regards,

Jeroen