New paint invalidation using paint property tree walk

third_party/WebKit/Source/wtf/Optional.h

Index: third_party/WebKit/Source/wtf/Optional.h
diff --git a/third_party/WebKit/Source/wtf/Optional.h b/third_party/WebKit/Source/wtf/Optional.h
index 1c2e422f522d6cb210e65f7ed6f71cf3597c6be4..d7c2029c781ba96bb687045d311524503df11a2c 100644
--- a/third_party/WebKit/Source/wtf/Optional.h
+++ b/third_party/WebKit/Source/wtf/Optional.h
@@ -51,6 +51,8 @@ public:
     T* operator->() { ASSERT_WITH_SECURITY_IMPLICATION(m_ptr); return m_ptr; }
     const T* operator->() const { ASSERT_WITH_SECURITY_IMPLICATION(m_ptr); return m_ptr; }
 
+    T* get() const { return m_ptr; }
+
     template <typename... Args>
     void emplace(Args&&... args)
     {