Revert "Revert of Fix update of validity cache value, so that it reflects the correct state of any …

Source/core/html/HTMLFormControlElement.h

Index: Source/core/html/HTMLFormControlElement.h
diff --git a/Source/core/html/HTMLFormControlElement.h b/Source/core/html/HTMLFormControlElement.h
index b6781d3eabc01255730e0d7b2c48a1e7c60ceb89..ce5a4fdd1d7f905b07fe2245bbb8da7bffab4cef 100644
--- a/Source/core/html/HTMLFormControlElement.h
+++ b/Source/core/html/HTMLFormControlElement.h
@@ -181,6 +181,8 @@ private:
     // Cache of valid().
     // But "candidate for constraint validation" doesn't affect m_isValid.
     bool m_isValid : 1;
+    // Dirty flag that controls updating valid() cache.
+    bool m_validityIsDirty : 1;
 
     bool m_wasChangedSinceLastFormControlChangeEvent : 1;
     bool m_wasFocusedByMouse : 1;