Fix double to integer conversions in runtime string indexing.

src/runtime.cc

 // Copyright 2006-2009 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 1647 matching lines @@
   RUNTIME_ASSERT(index->IsNumber());
 
   uint32_t i = 0;
   if (index->IsSmi()) {
     int value = Smi::cast(index)->value();
     if (value < 0) return Heap::nan_value();
     i = value;
   } else {
     ASSERT(index->IsHeapNumber());
     double value = HeapNumber::cast(index)->value();
-    i = static_cast<uint32_t>(value);
+    i = static_cast<uint32_t>(DoubleToInteger(value));
   }
 
   // Flatten the string.  If someone wants to get a char at an index
   // in a cons string, it is likely that more indices will be
   // accessed.
   Object* flat = subject->TryFlatten();
   if (flat->IsFailure()) return flat;
   subject = String::cast(flat);
 
   if (i >= static_cast<uint32_t>(subject->length())) {
@@ skipping 8625 matching lines @@
   } else {
     // Handle last resort GC and make sure to allow future allocations
     // to grow the heap without causing GCs (if possible).
     Counters::gc_last_resort_from_js.Increment();
     Heap::CollectAllGarbage(false);
   }
 }
 
 
 } }  // namespace v8::internal