Reduce signal sender thread stack size to 32k.

src/objects-inl.h

 // 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 2006 matching lines @@
 
 
 DescriptorArray::WhitenessWitness::~WhitenessWitness() {
   marking_->LeaveNoMarkingScope();
 }
 
 
 template<typename Shape, typename Key>
 int HashTable<Shape, Key>::ComputeCapacity(int at_least_space_for) {
   const int kMinCapacity = 32;
-  int capacity = RoundUpToPowerOf2(at_least_space_for * 2);
+  int capacity = SignedRoundUpToPowerOf2(at_least_space_for * 2);
   if (capacity < kMinCapacity) {
     capacity = kMinCapacity;  // Guarantee min capacity.
   }
   return capacity;
 }
 
 
 template<typename Shape, typename Key>
 int HashTable<Shape, Key>::FindEntry(Key key) {
   return FindEntry(GetIsolate(), key);
@@ skipping 2713 matching lines @@
 #undef WRITE_INT_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_