Switch from `Float32` to `Uint16` for encoding colors in buffers

[mourner]

Currently we use a pair of Float32 values to represent a color value in WebGL buffers:

mapbox-gl-js/src/data/program_configuration.js

Lines 169 to 170 in 4eeefae

	type: 'Float32',
	components: type === 'color' ? 2 : 1,

Using a pair of Uint16 instead should be enough precision while cutting the amount of data necessary to represent data-driven color properties in half, which might be a nice low hanging fruit to optimize performance in styles that extensively use data-driven colors (such as Mapbox core styles).

[Beilinson]

Any news on this ticket?