Refactor wasm feature gates.

src/ast/flags.rs

@@ -1,5 +1,9 @@
 //! Module defining script options.
 
+use std::ops::{Add, AddAssign, BitAnd, BitAndAssign, BitOr, BitOrAssign, Not, Sub, SubAssign};
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
+
 /// A type representing the access mode of a function.
 #[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
 pub enum FnAccess {
@@ -9,10 +13,6 @@ pub enum FnAccess {
     Private,
 }
 
-use std::ops::{Add, AddAssign, BitAnd, BitAndAssign, BitOr, BitOrAssign, Not, Sub, SubAssign};
-#[cfg(feature = "no_std")]
-use std::prelude::v1::*;
-
 /// A type that holds a configuration option with bit-flags.
 /// Exported under the `internals` feature only.
 #[derive(PartialEq, Eq, Copy, Clone, Hash, Default)]