Update src/core/data-structures/curve.js

Co-authored-by: Justin Ridgewell <[email protected]>

Author: rcebulko

src/core/data-structures/curve.js

@@ -18,7 +18,6 @@
 // the type system during compile time.
 import {NormTimeDef} from '../types/date';
 import {isString} from '../types';
-import {once} from '../types/function';
 
 /**
  * A CurveDef is a function that returns a normtime value (0 to 1) for another