[FIX] Fix undefined `this` in CanvasFont (#1320)
[FIX] Fix undefined `this` in CanvasFont (#1320)

Move normalizeCharSet into a member function so that it can access `this`

sereepap2029/playcanvas,aidinabedi/playcanvas-engine,sereepap2029/playcanvas,MicroWorldwide/PlayCanvas,aidinabedi/playcanvas-engine,MicroWorldwide/PlayCanvas,sereepap2029/playcanvas,playcanvas/engine,playcanvas/engine