R1:d3f4af4a3a0b

Add more layout constraints to tokenizer CSS to prevent layout issues with Chinese glyphs in Firefox 73

Summary:
Fixes T13495. See that task for details.

Tokenizer tokens which contain Chinese glyphs are slightly taller than normal tokens in Firefox 73, and at some non-100% zoom levels in other browsers.

This cauess the tokenizer list to layout and line break oddly.

Fix this by clamping tokenizer sizes more aggressively. Specifying a `max-height` means they can no longer line wrap, so this also…