Implement proper module linking.

test/mjsunit/harmony/module-resolution.js

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 15 matching lines @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 // Flags: --harmony-modules --harmony-scoping
 
 // Test basic module interface inference.
 
 "use strict";
 
 print("begin.")
 
+
 export let x = print("0")
 
 export module B = A.B
 
 export module A {
   export let x = print("1")
   export let f = function() { return B.x }
   export module B {
     module BB = B
     export BB, x
     let x = print("2")
-    let y = print("3")
+    var y = print("3")
     let Ax = A.x
+    try { A.y } catch (e) {}  // throws
+    let Az = A.z  // undefined
+    let Az2 = z  // undefined
+    A.g()  // hoisted
+    g()  // hoisted
     let ABx = A.B.x
-    let Ay = A.y
+    let ABy = A.B.y
+    let Bx = B.x
+    let By = B.y
     let BBx = BB.x
+    let BBy = BB.y
     let Af = A.f
     function f(x,y) { return x }
   }
   export let y = print("4")
+  export var z = print("4.1")
+  export function g() {}
   let Ax = A.x
   let Bx = B.x
   let ABx = A.B.x
   module C {
     export let z = print("5")
     export module D = B
     // TODO(rossberg): turn these into proper negative test cases once we have
     // suitable error messages.
     // import C.z  // multiple declarations
     import x from B
@@ skipping 19 matching lines @@
     // import A2.*  // unbound variable A2
   }
 }
 
 export module E {
   export let xx = x
   export y, B
   let Bx = B.x
   // TODO(rossberg): Handle import *.
   // import A.*
+  module B = A.B
+  let y = A.y
 }
 
 export module M1 {
   export module A2 = M2
 }
 export module M2 {
   export module A1 = M1
 }
 
 // TODO(rossberg): turn these into proper negative test cases once we have
@@ skipping 25 matching lines @@
 export module External at "external.js"
 export module External1 = External
 //export module ExternalA = External.A
 export module InnerExternal {
   export module E at "external.js"
 }
 export module External2 = InnerExternal.E
 //export let xxx = InnerExternal.E.A.x
 
 print("end.")