[runtime] Don't call GetArrayKeys on proxies.

src/js/array.js

Index: src/js/array.js
diff --git a/src/js/array.js b/src/js/array.js
index d9b097c84727e2aa7beb843b8895b46f25d85cd8..1406df336d03825cb8dac8f47abd0abd2f058323 100644
--- a/src/js/array.js
+++ b/src/js/array.js
@@ -1049,7 +1049,7 @@ function InnerArraySort(array, length, comparefn) {
   var CopyFromPrototype = function CopyFromPrototype(obj, length) {
     var max = 0;
     for (var proto = %_GetPrototype(obj); proto; proto = %_GetPrototype(proto)) {
-      var indices = %GetArrayKeys(proto, length);
+      var indices = IS_PROXY(proto) ? length : %GetArrayKeys(proto, length);

[Camillo Bruni, 2016/03/29 11:34:57]

aah quelle elegance!

       if (IS_NUMBER(indices)) {
         // It's an interval.
         var proto_length = indices;
@@ -1077,7 +1077,7 @@ function InnerArraySort(array, length, comparefn) {
   // elements in that range.
   var ShadowPrototypeElements = function(obj, from, to) {
     for (var proto = %_GetPrototype(obj); proto; proto = %_GetPrototype(proto)) {
-      var indices = %GetArrayKeys(proto, to);
+      var indices = IS_PROXY(proto) ? to : %GetArrayKeys(proto, to);
       if (IS_NUMBER(indices)) {
         // It's an interval.
         var proto_length = indices;