This is a "simplified" implementation of 'ic', similar to what Safari Preview
currently supports: it only considers the advance of U+6C34 if found in the
first available font, and otherwise falls back to the default of 1em.
(The spec allows for this "in cases where it is impossible or impractical to
determine the ideographic advance measure".)
Differential Revision: https://phabricator.services.mozilla.com/D132818
We never fast-reject numbers (because they could be part of a product). Without
this refactoring we'd accept stuff like calc(10) and crash during the evaluation
for obvious reasons.
Differential Revision: https://phabricator.services.mozilla.com/D63401
This is the meat of the patch. There are a couple improvements done in a couple
later patches which should hopefully be straight-forward.
Differential Revision: https://phabricator.services.mozilla.com/D63397
