backout changeset 3e9d9aa535c7 (bug 1018551) due to MS Sans Serif regression with Thai system locale (see bug 1020826).
backout changeset 48b74ab18f92 (bug 1018034) due to MS Sans Serif regression with Thai system locale (see bug 1020826).
backout changeset 59b2dd6b5048 (bug 985220) due to MS Sans Serif regression with Thai system locale (see bug 1020826).