message: Clear label states cache on projection change.
  Also, clear it on call to MapView's dispose method.
diff: @@ -1075,6 +1075,7 @@ export class MapView extends THREE.EventDispatcher {
  dataSource.dispose();
  }
  this.m_visibleTiles.clearTileCache();
  + this.m_textElementsRenderer.clearRenderStates();
  this.m_renderer.dispose();
  this.m_imageCache.clear();
  @@ -1470,6 +1471,7 @@ export class MapView extends THREE.EventDispatcher {
  this.m_visibleTileSetOptions.projection = projection;
  this.updatePolarDataSource();
  this.clearTileCache();
  + this.textElementsRenderer.clearRenderStates();
  this.m_visibleTiles = new VisibleTileSet(
  new FrustumIntersection(
  this.m_camera,
  