submit() in submit event handler should not contains a value of a submit button.

third_party/WebKit/Source/core/html/HTMLButtonElement.cpp

Index: third_party/WebKit/Source/core/html/HTMLButtonElement.cpp
diff --git a/third_party/WebKit/Source/core/html/HTMLButtonElement.cpp b/third_party/WebKit/Source/core/html/HTMLButtonElement.cpp
index 5c470732e20b668453f18a82e0712a7c4c5c5324..a39f1c9850a5ffd7073688e18e438f02980b85f2 100644
--- a/third_party/WebKit/Source/core/html/HTMLButtonElement.cpp
+++ b/third_party/WebKit/Source/core/html/HTMLButtonElement.cpp
@@ -114,10 +114,8 @@ void HTMLButtonElement::defaultEventHandler(Event* event)
 {
     if (event->type() == EventTypeNames::DOMActivate && !isDisabledFormControl()) {
         if (form() && m_type == SUBMIT) {
-            m_isActivatedSubmit = true;
-            form()->prepareForSubmission(event);
+            form()->prepareForSubmission(event, this);
             event->setDefaultHandled();
-            m_isActivatedSubmit = false; // Do this in case submission was canceled.
         }
         if (form() && m_type == RESET) {
             form()->reset();