[kissfft-js] comply to strict-export-declare-modifiers lint rule

types/kissfft-js/index.d.ts

@@ -3,17 +3,16 @@
 // Definitions by: racerhere <https://github.com/racerhere>
 // Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped/types/kissfft-js
 
-declare abstract class AbstractKissFFT {
+export class FFT {
     constructor(size: number);
     forward(input: number[]): number[];
     inverse(input: number[]): number[];
     dispose(): void;
 }
 
-export class FFT extends AbstractKissFFT {
-}
-
-export class FFTR extends AbstractKissFFT {
-}
-
-export {}
+export class FFTR {
+    constructor(size: number);
+    forward(input: number[]): number[];
+    inverse(input: number[]): number[];
+    dispose(): void;
+}