Work around types.

Author: donmccurdy

src/subjects/MaterialSubject.ts

@@ -253,17 +253,18 @@ export class MaterialSubject extends Subject<MaterialDef, Material> {
 		}
 
 		// KHR_materials_anisotropy
+		// TODO(cleanup): Remove 'any' after https://github.com/three-types/three-ts-types/pull/472.
 		const anisotropy = def.getExtension<Anisotropy>('KHR_materials_anisotropy');
 		if (anisotropy) {
-			if (anisotropy.getAnisotropyStrength() !== target.anisotropy) {
-				if (target.anisotropy === 0) target.needsUpdate = true;
-				target.anisotropy = anisotropy.getAnisotropyStrength();
+			if (anisotropy.getAnisotropyStrength() !== (target as any).anisotropy) {
+				if ((target as any).anisotropy === 0) target.needsUpdate = true;
+				(target as any).anisotropy = anisotropy.getAnisotropyStrength();
 			}
-			if (anisotropy.getAnisotropyRotation() !== target.anisotropyRotation) {
-				target.anisotropyRotation = anisotropy.getAnisotropyRotation();
+			if (anisotropy.getAnisotropyRotation() !== (target as any).anisotropyRotation) {
+				(target as any).anisotropyRotation = anisotropy.getAnisotropyRotation();
 			}
 		} else {
-			target.anisotropy = 0;
+			(target as any).anisotropy = 0;
 		}
 
 		// KHR_materials_clearcoat