Refactor the Heap into ThreadHeap to prepare for per thread heaps

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

Index: third_party/WebKit/Source/platform/heap/PagePool.cpp
diff --git a/third_party/WebKit/Source/platform/heap/PagePool.cpp b/third_party/WebKit/Source/platform/heap/PagePool.cpp
index f88e90cf94d76e4d9c586a5e19e00845706d0eed..5d31522ce3bb04d360fd1ef5f878bd258768957f 100644
--- a/third_party/WebKit/Source/platform/heap/PagePool.cpp
+++ b/third_party/WebKit/Source/platform/heap/PagePool.cpp
@@ -102,7 +102,7 @@ void OrphanedPagePool::decommitOrphanedPages()
             } else {
                 page->~BasePage();
                 clearMemory(memory);
-                Heap::freePagePool()->addFreePage(index, memory);
+                page->heap()->threadState()->freePagePool()->addFreePage(index, memory);
             }
 
             PoolEntry* deadEntry = entry;