Strange wl-textfield rendering issue in Edge and older Chrome

[chrissterling]

It looks like something that wl-textfield uses isn't supported, but can't figure out what. The weightless buttons and popup menus all work, along with all the other lit-element features, so seems a shame to not get this going. See image for correct and failed renders...

Chrome 53 support is useful as it comes as the default browser on several Android dongle computers, and I'm sure Edge's user is keen for a fix too.