Optimize getSpriteTargetByName

[GarboMuffin]

O(n) right now, can be optimized to a map lookup

7% of runtime in a big project

[yuri-kiss]

So store the name in a map [NAME=>SPRITE]?

[FurryR]

So store the name in a map [NAME=>SPRITE]?

class Runtime {
  // ...
  targetMap: Map<string /** id **/, RenderedTarget>;
};