Migrate LowPassFilter

Summary: _typescript_

Reviewed By: danielbuechele

Differential Revision: D16764120

fbshipit-source-id: 03185c74f3a1e753089ea550d3f193027aae9424

src/utils/LowPassFilter.tsx

@@ -6,7 +6,7 @@
  */
 
 export default class LowPassFilter {
-  constructor(smoothing?: number = 0.9) {
+  constructor(smoothing: number = 0.9) {
     this.smoothing = smoothing;
     this.buffer = [];
     this.bufferMaxSize = 5;