Explicitly escape for "unsafe" mode in definevar.
Review Request #11953 — Created Jan. 21, 2022 and submitted
definevartag was relying on
strbeing treated as unsafe strings,
but in the test suite that seems to no longer be the case for template
tags (though I'm not finding much in the documentation about this). This
change updates it to explicitly call
escapeinstead of relying on the
type-checking deeper down.
Ran unit tests.