Add WTF_EXPORT to BitVector::OutOfLineBits

Source/wtf/BitVector.h

Index: Source/wtf/BitVector.h
diff --git a/Source/wtf/BitVector.h b/Source/wtf/BitVector.h
index 412bf50c0d8300b3ce8ec3c2a467791ff9f4c46a..e540725cd8b06d01583a10ca27d41116bc5450f0 100644
--- a/Source/wtf/BitVector.h
+++ b/Source/wtf/BitVector.h
@@ -194,7 +194,7 @@ private:
         return bits | (static_cast<uintptr_t>(1) << maxInlineBits());
     }
 
-    class OutOfLineBits {
+    class WTF_EXPORT OutOfLineBits {
     public:
         size_t numBits() const { return m_numBits; }
         size_t numWords() const { return (m_numBits + bitsInPointer() - 1) / bitsInPointer(); }