Merge pull request #16313 from kohlmannj/light-typedef-isLight

Add `isLight: true` class property to Light.d.ts

src/lights/Light.d.ts

@@ -12,6 +12,7 @@ export class Light extends Object3D {
 
   color: Color;
   intensity: number;
+	isLight: true;
   receiveShadow: boolean;
   shadow: LightShadow;
   /**