Dispatch change event for input type=checkbox when checked but value is null

Source/core/html/forms/InputType.cpp

Index: Source/core/html/forms/InputType.cpp
diff --git a/Source/core/html/forms/InputType.cpp b/Source/core/html/forms/InputType.cpp
index 7b714225fa912f078db351b7caa5d1885734b35f..bd09e3ef849a23b69a218ddc2285ac5083a4b432 100644
--- a/Source/core/html/forms/InputType.cpp
+++ b/Source/core/html/forms/InputType.cpp
@@ -547,6 +547,11 @@ bool InputType::storesValueSeparateFromAttribute()
     return true;
 }
 
+bool InputType::shouldDispatchFormControlChangeEvent(String& oldValue, String& newValue)
+{
+    return !equalIgnoringNullity(oldValue, newValue);
+}
+
 void InputType::setValue(const String& sanitizedValue, bool valueChanged, TextFieldEventBehavior eventBehavior)
 {
     element().setValueInternal(sanitizedValue, eventBehavior);