Revert of Revert of Hook up more import/exports in natives.

src/weak-collection.js

Index: src/weak-collection.js
diff --git a/src/weak-collection.js b/src/weak-collection.js
index 29ef5d497e1aa0468d52ef6f9a08b59c5ca794fa..0e71c7cc147494263ef0926a56e1de0ed335e065 100644
--- a/src/weak-collection.js
+++ b/src/weak-collection.js
@@ -88,7 +88,7 @@
                   DONT_ENUM | READ_ONLY);
 
 // Set up the non-enumerable functions on the WeakMap prototype object.
-$installFunctions(GlobalWeakMap.prototype, DONT_ENUM, [
+utils.InstallFunctions(GlobalWeakMap.prototype, DONT_ENUM, [
   "get", WeakMapGet,
   "set", WeakMapSet,
   "has", WeakMapHas,
@@ -158,7 +158,7 @@
                   DONT_ENUM | READ_ONLY);
 
 // Set up the non-enumerable functions on the WeakSet prototype object.
-$installFunctions(GlobalWeakSet.prototype, DONT_ENUM, [
+utils.InstallFunctions(GlobalWeakSet.prototype, DONT_ENUM, [
   "add", WeakSetAdd,
   "has", WeakSetHas,
   "delete", WeakSetDelete