Reduce ephemeron stack size reservation.

third_party/WebKit/Source/platform/heap/CallbackStack.cpp

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "platform/heap/CallbackStack.h"
 #include "wtf/PageAllocator.h"
 
 namespace blink {
 
+size_t const CallbackStack::kMinimalBlockSize = WTF::kPageAllocationGranularity / sizeof(CallbackStack::Item);
+
 CallbackStack::Block::Block(Block* next, size_t blockSize)
     : m_blockSize(blockSize)
 {
     // Allocated block size must be a multiple of WTF::kPageAllocationGranularity.
     ASSERT((m_blockSize * sizeof(Item)) % WTF::kPageAllocationGranularity == 0);
     m_buffer = static_cast<Item*>(WTF::allocPages(nullptr, m_blockSize * sizeof(Item), WTF::kPageAllocationGranularity, WTF::PageAccessible));
     RELEASE_ASSERT(m_buffer);
 
 #if ENABLE(ASSERT)
     clear();
@@ skipping 148 matching lines @@
 {
     for (Block* current = m_first; current; current = current->next()) {
         if (current->hasCallbackForObject(object))
             return true;
     }
     return false;
 }
 #endif
 
 } // namespace blink