[array] Change array indices handling for proxies in sort preprocessing

For JSProxies we filled a FixedArray with the numbers from 0 to
length - 1. Because all indices were assumed to be Smis, large array
indices on Proxies were not handled correctly.

R=jgruber@chromium.org

Bug: chromium:866314
Change-Id: I6a792e800f31617a6092b219ec82b0e05a83bf7b
Reviewed-on: https://chromium-review.googlesource.com/1146562Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Simon Zünd <szuend@google.com>
Cr-Commit-Position: refs/heads/master@{#54603}

src/runtime/runtime-array.cc

@@ -61,20 +61,14 @@ Object* RemoveArrayHolesGeneric(Isolate* isolate, Handle<JSReceiver> receiver,
   // For proxies, we do not collect the keys, instead we use all indices in
   // the full range of [0, limit).
   Handle<FixedArray> keys;
-  if (receiver->IsJSProxy()) {
-    CHECK(Smi::IsValid(limit));
-    keys = isolate->factory()->NewFixedArray(limit);
-    for (uint32_t i = 0; i < limit; ++i) {
-      keys->set(i, Smi::FromInt(i));
-    }
-  } else {
+  if (!receiver->IsJSProxy()) {
     keys = JSReceiver::GetOwnElementIndices(isolate, receiver,
                                             Handle<JSObject>::cast(receiver));
   }
 
   uint32_t num_undefined = 0;
   uint32_t current_pos = 0;
-  int num_indices = keys->length();
+  int num_indices = keys.is_null() ? limit : keys->length();
 
   // Compact keys with undefined values and moves non-undefined
   // values to the front.
@@ -86,7 +80,7 @@ Object* RemoveArrayHolesGeneric(Isolate* isolate, Handle<JSReceiver> receiver,
   //       Holes and 'undefined' are considered free spots.
   //       A hole is when HasElement(receiver, key) is false.
   for (int i = 0; i < num_indices; ++i) {
-    uint32_t key = NumberToUint32(keys->get(i));
+    uint32_t key = keys.is_null() ? i : NumberToUint32(keys->get(i));
 
     // We only care about array indices that are smaller than the limit.
     // The keys are sorted, so we can break as soon as we encounter the first.
@@ -143,7 +137,7 @@ Object* RemoveArrayHolesGeneric(Isolate* isolate, Handle<JSReceiver> receiver,
 
   // Deleting everything after the undefineds up unto the limit.
   for (int i = num_indices - 1; i >= 0; --i) {
-    uint32_t key = NumberToUint32(keys->get(i));
+    uint32_t key = keys.is_null() ? i : NumberToUint32(keys->get(i));
     if (key < current_pos) break;
     if (key >= limit) continue;