Avoid implicit size_t conversions on setting HeapObjectHeader::m_encoded.

third_party/WebKit/Source/platform/heap/HeapPage.h

 /*
  * Copyright (C) 2013 Google Inc. 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
@@ skipping 167 matching lines @@
         // for an freed entry.  Given that the smallest entry size is
         // allocationGranurarity, HeapObjectHeader must fit into the size.
         static_assert(sizeof(HeapObjectHeader) <= allocationGranularity, "size of HeapObjectHeader must be smaller than allocationGranularity");
 #if CPU(64BIT)
         static_assert(sizeof(HeapObjectHeader) == 8, "size of HeapObjectHeader must be 8 byte aligned");
 #endif
 
         ASSERT(gcInfoIndex < GCInfoTable::maxIndex);
         ASSERT(size < nonLargeObjectPageSizeMax);
         ASSERT(!(size & allocationMask));
-        m_encoded = (gcInfoIndex << headerGCInfoIndexShift) | size | (gcInfoIndex == gcInfoIndexForFreeListHeader ? headerFreedBitMask : 0);
+        m_encoded = static_cast<uint32_t>((gcInfoIndex << headerGCInfoIndexShift) | size | (gcInfoIndex == gcInfoIndexForFreeListHeader ? headerFreedBitMask : 0));
     }
 
     NO_SANITIZE_ADDRESS
     bool isFree() const { return m_encoded & headerFreedBitMask; }
     NO_SANITIZE_ADDRESS
     bool isPromptlyFreed() const { return (m_encoded & headerPromptlyFreedBitMask) == headerPromptlyFreedBitMask; }
     NO_SANITIZE_ADDRESS
     void markPromptlyFreed() { m_encoded |= headerPromptlyFreedBitMask; }
     size_t size() const;
 
     NO_SANITIZE_ADDRESS
     size_t gcInfoIndex() const { return (m_encoded & headerGCInfoIndexMask) >> headerGCInfoIndexShift; }
     NO_SANITIZE_ADDRESS
-    void setSize(size_t size) { m_encoded = size | (m_encoded & ~headerSizeMask); }
+    void setSize(size_t size)
+    {
+        ASSERT(size < nonLargeObjectPageSizeMax);
+        m_encoded = static_cast<uint32_t>(size) | (m_encoded & ~headerSizeMask);
+    }
     bool isMarked() const;
     void mark();
     void unmark();
     void markDead();
     bool isDead() const;
 
     Address payload();
     size_t payloadSize();
     Address payloadEnd();
 
@@ skipping 656 matching lines @@
         SET_MEMORY_ACCESSIBLE(result, allocationSize - sizeof(HeapObjectHeader));
         ASSERT(findPageFromAddress(headerAddress + allocationSize - 1));
         return result;
     }
     return outOfLineAllocate(allocationSize, gcInfoIndex);
 }
 
 } // namespace blink
 
 #endif // HeapPage_h