Option, checkbox and radio should support ':default' selector

third_party/WebKit/Source/core/html/forms/BaseButtonInputType.cpp

Index: third_party/WebKit/Source/core/html/forms/BaseButtonInputType.cpp
diff --git a/third_party/WebKit/Source/core/html/forms/BaseButtonInputType.cpp b/third_party/WebKit/Source/core/html/forms/BaseButtonInputType.cpp
index 9eb0bbaf3e4c91e2a48d2369d6d9f5453b6e3163..8cf28d0579d08cb197b9d32a3df55c1dd534324e 100644
--- a/third_party/WebKit/Source/core/html/forms/BaseButtonInputType.cpp
+++ b/third_party/WebKit/Source/core/html/forms/BaseButtonInputType.cpp
@@ -34,6 +34,7 @@
 #include "core/HTMLNames.h"
 #include "core/dom/Text.h"
 #include "core/dom/shadow/ShadowRoot.h"
+#include "core/html/HTMLFormElement.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "core/layout/LayoutButton.h"
@@ -82,4 +83,11 @@ void BaseButtonInputType::setValue(const String& sanitizedValue, bool, TextField
     element().setAttribute(valueAttr, AtomicString(sanitizedValue));
 }
 
+bool BaseButtonInputType::matchesDefaultPseudoClass()
+{
+    // HTMLFormElement::findDefaultButton() traverses the tree. So we check
+    // canBeSuccessfulSubmitButton() first for early return.
+    return canBeSuccessfulSubmitButton() && element().form() && element().form()->findDefaultButton() == &element();
+}
+
 } // namespace blink