VectorComparer should check null.

Source/wtf/Vector.h

Index: Source/wtf/Vector.h
diff --git a/Source/wtf/Vector.h b/Source/wtf/Vector.h
index ed58774fe7f2980cc6b536181da877dc8b28fb81..210e2a9abb021125c06eefcd3e6c9e03b5c61fd9 100644
--- a/Source/wtf/Vector.h
+++ b/Source/wtf/Vector.h
@@ -224,6 +224,11 @@ static const size_t kInitialVectorSize = WTF_VECTOR_INITIAL_SIZE;
     {
         static bool compare(const T* a, const T* b, size_t size)
         {
+            if (!a || !b) {

[tkent, 2014/06/16 04:42:26]

I recommend to write popular case at first.  e.g.

if (LIKELY(a && b))
    return std::equal(...);
return !a && !b;

[yoichio, 2014/06/16 04:58:45]

Done.

+                if (!a && !b)
+                    return true;
+                return false;
+            }
             return std::equal(a, a + size, b);
         }
     };