Wide outlines cause incorrect label rendering

[mramato]

Given this snippet:

var viewer = new Cesium.Viewer('cesiumContainer');

viewer.entities.add({
    position : Cesium.Cartesian3.fromDegrees(-75.1641667, 39.9522222),
    label : {
        text : 'abcdefghijklmnopqrstuvwxyz',
        font : '24px serif',
        fillColor : Cesium.Color.SKYBLUE,
        outlineColor : Cesium.Color.WHITE,
        outlineWidth : 6,
        scale: 3,
        style : Cesium.LabelStyle.FILL_AND_OUTLINE
    }
});

It looks like this:

Expected is something like this (drawn as a single billboard):

This is a tough one. Our kerning actually looks correct here. The problem is that the billboard drawn on top of each other rather than blending together naturally. I'm not sure it's possible for us to fix this with our current label techniques because the letters have to be drawn together for the blending to work (look at the qr for an example).

I also noticed something is up with the f, the top right is cut off, this is probably a separate bug..

[pjcozzi]

CC #2521