fix type for getFlexBasis (#1222)

Summary:
`getFlexBasis` returns `Value` not a `number`

source:
https://github.com/facebook/yoga/blob/main/javascript/src_native/Node.hh#L145

Pull Request resolved: https://github.com/facebook/yoga/pull/1222

Reviewed By: rozele, cipolleschi

Differential Revision: D42818313

Pulled By: NickGerleman

fbshipit-source-id: cbcfe1b5d353ed86303a4de987e66f86b77ced1b

javascript/src_js/wrapAsm.d.ts

@@ -92,7 +92,7 @@ export type Node = {
   getComputedTop(): number,
   getComputedWidth(): number,
   getDisplay(): Display,
-  getFlexBasis(): number,
+  getFlexBasis(): Value,
   getFlexDirection(): FlexDirection,
   getFlexGrow(): number,
   getFlexShrink(): number,