Well, here're my 2 cents guys.
I never had to work with emojis input, or dig so deeply in fonts specifications, so I don't fully understand the internals.
1st - I managed to create a font (here) with FontForge that includes OpenSans, and Emojis Symbols.
Using a custom font/emojis allows you to have consistency across OSs. Yet, I placed the chars in a low unicode position, filling some gaps in OpenSource for arabic chars or something like that...
2nd - Emojis Symbols and EmojiOne have some solid fills emojis, so you can tint them as you want. I included a distance field as well... so you could use BitmapFont.
Bah, the post was too long apparently, was automatically cut-off... I'm retyping this
test repo ...
My point is, use the best of both worlds, build a custom font, but detecting the charcode as explained in the source code of the repo... and mapping custom emojis to those "apple" utf16 unicode ranges.
Or (for rendering not StageText) download AppleColorEmoji ttf (is over 75mb) embed in ur code, use TrueType rendering, textfield.isHtml=true, and append the html ( <font face="...> ).
Or just draw the bitmapdata for the stagetext... and overload the GPU with textures.