Merge revision 6500-6600 from bleeding_edge to the isolates branch.

src/builtins.cc

Index: src/builtins.cc
===================================================================
--- src/builtins.cc	(revision 7030)
+++ src/builtins.cc	(working copy)
@@ -753,35 +753,39 @@
 
   int n_arguments = args.length() - 1;
 
-  // Return empty array when no arguments are supplied.
-  if (n_arguments == 0) {
-    return AllocateEmptyJSArray(heap);
-  }
-
   int relative_start = 0;
-  Object* arg1 = args[1];
-  if (arg1->IsSmi()) {
-    relative_start = Smi::cast(arg1)->value();
-  } else if (!arg1->IsUndefined()) {
-    return CallJsBuiltin(isolate, "ArraySplice", args);
+  if (n_arguments > 0) {
+    Object* arg1 = args[1];
+    if (arg1->IsSmi()) {
+      relative_start = Smi::cast(arg1)->value();
+    } else if (!arg1->IsUndefined()) {
+      return CallJsBuiltin(isolate, "ArraySplice", args);
+    }
   }
   int actual_start = (relative_start < 0) ? Max(len + relative_start, 0)
                                           : Min(relative_start, len);
 
   // SpiderMonkey, TraceMonkey and JSC treat the case where no delete count is
-  // given differently from when an undefined delete count is given.
+  // given as a request to delete all the elements from the start.
+  // And it differs from the case of undefined delete count.
   // This does not follow ECMA-262, but we do the same for
   // compatibility.
-  int delete_count = len;
-  if (n_arguments > 1) {
-    Object* arg2 = args[2];
-    if (arg2->IsSmi()) {
-      delete_count = Smi::cast(arg2)->value();
-    } else {
-      return CallJsBuiltin(isolate, "ArraySplice", args);
+  int actual_delete_count;
+  if (n_arguments == 1) {
+    ASSERT(len - actual_start >= 0);
+    actual_delete_count = len - actual_start;
+  } else {
+    int value = 0;  // ToInteger(undefined) == 0
+    if (n_arguments > 1) {
+      Object* arg2 = args[2];
+      if (arg2->IsSmi()) {
+        value = Smi::cast(arg2)->value();
+      } else {
+        return CallJsBuiltin(isolate, "ArraySplice", args);
+      }
     }
+    actual_delete_count = Min(Max(value, 0), len - actual_start);
   }
-  int actual_delete_count = Min(Max(delete_count, 0), len - actual_start);
 
   JSArray* result_array = NULL;
   if (actual_delete_count == 0) {