syscall/js: fix comments

As js.TypedArray no longer exists, the comment should be updated.

Change-Id: Idd1087c8007afc90307fdd965f28d3be8d8cd73e
Reviewed-on: https://go-review.googlesource.com/c/go/+/180097Reviewed-by: Richard Musiol <neelance@gmail.com>

src/syscall/js/js.go

@@ -105,7 +105,6 @@ func Global() Value {
 //  | Go                     | JavaScript             |
 //  | ---------------------- | ---------------------- |
 //  | js.Value               | [its value]            |
-//  | js.TypedArray          | typed array            |
 //  | js.Func                | function               |
 //  | nil                    | null                   |
 //  | bool                   | boolean                |