The logic around here is a bit tricky, because -moz-linear-gradient() shares this codepath. Here's how things were going wrong: * The -moz-linear-gradient syntax allows an angle (e.g. "30deg") to be followed by an optional box-position (e.g. "top right") before eventually requiring a comma and then some color stops. * In contrast, the -webkit-linear-gradient syntax does NOT allow a box-position there (unless the box-position is by itself, without an angle). * So, for -webkit-linear-gradient, we (correctly) skipped the box-position parsing code, if we've seen an angle already. * BUT: in skipping that code, we *also* inadvertantly skipped the code that enforces that we eventually see a comma before we get to the color stops. So, we incorrectly accept some -webkit-linear-gradient() expressions that are missing a comma that really should be mandatory. So, this patch adds a special case for -webkit-linear-gradient that preemptively bails if we get an angle that's not followed by a comma. (With that, we can also simplify the condition around the box position parsing, too.) Review commit: https://reviewboard.mozilla.org/r/132536/diff/#index_header See other reviews: https://reviewboard.mozilla.org/r/132536/