Count usage of reading HTMLInputElement::checked during click event handler.

Source/core/html/forms/RadioInputType.cpp

Index: Source/core/html/forms/RadioInputType.cpp
diff --git a/Source/core/html/forms/RadioInputType.cpp b/Source/core/html/forms/RadioInputType.cpp
index c07f51e0dd40ad5c7ffe1ce6f417b17ab08add51..239f8d6209ce06496e2a6cb30606936c3f7f40b5 100644
--- a/Source/core/html/forms/RadioInputType.cpp
+++ b/Source/core/html/forms/RadioInputType.cpp
@@ -180,7 +180,7 @@ PassOwnPtrWillBeRawPtr<ClickHandlingState> RadioInputType::willDispatchClick()
     state->checked = element().checked();
     state->checkedRadioButton = element().checkedRadioButtonForGroup();
     element().setChecked(true, DispatchChangeEvent);
-
+    m_isInClickHandler = true;
     return state.release();
 }
 
@@ -199,7 +199,7 @@ void RadioInputType::didDispatchClick(Event* event, const ClickHandlingState& st
     } else {
         element().dispatchChangeEventIfNeeded();
     }
-
+    m_isInClickHandler = false;
     // The work we did in willDispatchClick was default handling.
     event->setDefaultHandled();
 }