Improve fast to slow elements conversion:

src/runtime.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1648 matching lines @@
                                            index,
                                            last_match_info);
   if (result.is_null()) return Failure::Exception();
   return *result;
 }
 
 
 RUNTIME_FUNCTION(MaybeObject*, Runtime_RegExpConstructResult) {
   ASSERT(args.length() == 3);
   CONVERT_SMI_ARG_CHECKED(elements_count, 0);
-  if (elements_count > JSArray::kMaxFastElementsLength) {
+  if (elements_count < 0 ||
+      elements_count > FixedArray::kMaxLength ||
+      !Smi::IsValid(elements_count)) {
     return isolate->ThrowIllegalOperation();
   }
   Object* new_object;
   { MaybeObject* maybe_new_object =
         isolate->heap()->AllocateFixedArrayWithHoles(elements_count);
     if (!maybe_new_object->ToObject(&new_object)) return maybe_new_object;
   }
   FixedArray* elements = FixedArray::cast(new_object);
   { MaybeObject* maybe_new_object = isolate->heap()->AllocateRaw(
       JSRegExpResult::kSize, NEW_SPACE, OLD_POINTER_SPACE);
@@ skipping 11014 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     isolate->counters()->gc_last_resort_from_js()->Increment();
     isolate->heap()->CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal