Revert "Remove support for MSVC"

sky/engine/wtf/RefPtr.h

Index: sky/engine/wtf/RefPtr.h
diff --git a/sky/engine/wtf/RefPtr.h b/sky/engine/wtf/RefPtr.h
index a8c17270608ff9595a3a310e7490e1fe2780ba01..5b0ea80ca50452738cc18f9a247c814b02d3ffbf 100644
--- a/sky/engine/wtf/RefPtr.h
+++ b/sky/engine/wtf/RefPtr.h
@@ -44,8 +44,10 @@ namespace WTF {
         ALWAYS_INLINE RefPtr(const RefPtr& o) : m_ptr(o.m_ptr) { refIfNotNull(m_ptr); }
         template<typename U> RefPtr(const RefPtr<U>& o, EnsurePtrConvertibleArgDecl(U, T)) : m_ptr(o.get()) { refIfNotNull(m_ptr); }
 
+#if COMPILER_SUPPORTS(CXX_RVALUE_REFERENCES)
         RefPtr(RefPtr&& o) : m_ptr(o.m_ptr) { o.m_ptr = 0; }
         RefPtr& operator=(RefPtr&&);
+#endif
 
         // See comments in PassRefPtr.h for an explanation of why this takes a const reference.
         template<typename U> RefPtr(const PassRefPtr<U>&, EnsurePtrConvertibleArgDecl(U, T));
@@ -106,6 +108,7 @@ namespace WTF {
         return *this;
     }
 
+#if COMPILER_SUPPORTS(CXX_RVALUE_REFERENCES)
     template<typename T> inline RefPtr<T>& RefPtr<T>::operator=(RefPtr&& o)
     {
         // FIXME: Instead of explicitly casting to RefPtr&& here, we should use std::move, but that requires us to
@@ -114,6 +117,7 @@ namespace WTF {
         swap(ptr);
         return *this;
     }
+#endif
 
     template<typename T> template<typename U> inline RefPtr<T>& RefPtr<T>::operator=(const RefPtr<U>& o)
     {