Mark shouldMarkObject(), arenaForNormalPage() accessors as const.

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

Index: third_party/WebKit/Source/platform/heap/HeapPage.h
diff --git a/third_party/WebKit/Source/platform/heap/HeapPage.h b/third_party/WebKit/Source/platform/heap/HeapPage.h
index 6659ddc8c858a1b4174eb86756127ba1ed54a198..4ae9945859393b7333b3fbb9f8bb11fbdae9d8a7 100644
--- a/third_party/WebKit/Source/platform/heap/HeapPage.h
+++ b/third_party/WebKit/Source/platform/heap/HeapPage.h
@@ -494,7 +494,7 @@ public:
         return sizeof(NormalPage) + paddingSize;
     }
 
-    NormalPageArena* arenaForNormalPage();
+    inline NormalPageArena* arenaForNormalPage() const;
 
 private:
     HeapObjectHeader* findHeaderFromAddress(Address);
@@ -925,6 +925,11 @@ inline Address NormalPageArena::allocateObject(size_t allocationSize, size_t gcI
     return outOfLineAllocate(allocationSize, gcInfoIndex);
 }
 
+inline NormalPageArena* NormalPage::arenaForNormalPage() const
+{
+    return static_cast<NormalPageArena*>(arena());
+}
+
 } // namespace blink
 
 #endif // HeapPage_h