Use import/export for more functions (instead of js builtins object).

src/js/harmony-sharedarraybuffer.js

Index: src/js/harmony-sharedarraybuffer.js
diff --git a/src/js/harmony-sharedarraybuffer.js b/src/js/harmony-sharedarraybuffer.js
index 3a72d6c353b1c8df75f96484152100e78d23e709..01983498f6223105ead3c801ef5917747715e68c 100644
--- a/src/js/harmony-sharedarraybuffer.js
+++ b/src/js/harmony-sharedarraybuffer.js
@@ -10,13 +10,18 @@
 
 var GlobalSharedArrayBuffer = global.SharedArrayBuffer;
 var GlobalObject = global.Object;
+var ToPositiveInteger;
 var toStringTagSymbol = utils.ImportNow("to_string_tag_symbol");
 
+utils.Import(function(from) {
+  ToPositiveInteger = from.ToPositiveInteger;
+})
+
 // -------------------------------------------------------------------
 
 function SharedArrayBufferConstructor(length) { // length = 1
   if (%_IsConstructCall()) {
-    var byteLength = $toPositiveInteger(length, kInvalidArrayBufferLength);
+    var byteLength = ToPositiveInteger(length, kInvalidArrayBufferLength);
     %ArrayBufferInitialize(this, byteLength, kShared);
   } else {
     throw MakeTypeError(kConstructorNotFunction, "SharedArrayBuffer");