add layout-helper.d.ts
add layout-helper.d.ts

hdeshev/NativeScript,genexliu/NativeScript,hdeshev/NativeScript,NativeScript/NativeScript,genexliu/NativeScript,NativeScript/NativeScript,hdeshev/NativeScript,NativeScript/NativeScript,genexliu/NativeScript,NativeScript/NativeScript,NativeScript/NativeScript