Initial ES modules support

lib/stdlib/globals.js

@@ -1,20 +1,7 @@
-// The stdlib, compiled in front of every program. Its files are joined in the
-// order of `STDLIB` in compiler/src/main.rs, and this one is first
-//
-// Built on the natives in compiler/src/native.rs, the common layer of
-// operations on primitive values. The compiler's own code for operators (`+` on
-// strings and so on) uses those natives directly, not these functions.
-//
-// Restrictions:
-// - The prototypes of `String`, `Number`, `Boolean` and `Array` are fixed:
-//   the compiler reads them by name, as the prototypes of the primitives and of
-//   arrays. User code may not change them (no monkey-patching)
-// - `new String(x)`, `new Number(x)` and `new Boolean(x)` (wrapper objects) are
-//   not supported. These functions only convert
-//
-// Needs `typeof`. `String.prototype.concat` is not here, because it needs rest
-// params, which need arrays. `console.log` prints one arg only, for the same
-// reason
+// The global values that are not functions. `undefined` is a binding like any
+// other: a global name refers to the prelude's export of that name (see
+// prelude.js)
 
-const NaN = 0 / 0;
-const Infinity = 1 / 0;
+export const undefined = void 0;
+export const NaN = 0 / 0;
+export const Infinity = 1 / 0;