Remove DialogElement runtime flag (status=stable)

Source/core/loader/FormSubmission.cpp

 /*
  * Copyright (C) 2010 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 90 matching lines @@
 void FormSubmission::Attributes::updateEncodingType(const String& type)
 {
     m_encodingType = parseEncodingType(type);
     m_isMultiPartForm = (m_encodingType == "multipart/form-data");
 }
 
 FormSubmission::Method FormSubmission::Attributes::parseMethodType(const String& type)
 {
     if (equalIgnoringCase(type, "post"))
         return FormSubmission::PostMethod;
-    if (RuntimeEnabledFeatures::dialogElementEnabled() && equalIgnoringCase(type, "dialog"))
+    if (equalIgnoringCase(type, "dialog"))
         return FormSubmission::DialogMethod;
     return FormSubmission::GetMethod;
 }
 
 void FormSubmission::Attributes::updateMethodType(const String& type)
 {
     m_method = parseMethodType(type);
 }
 
 String FormSubmission::Attributes::methodString(Method method)
@@ skipping 157 matching lines @@
             frameRequest.resourceRequest().setHTTPContentType(m_contentType);
         else
             frameRequest.resourceRequest().setHTTPContentType(m_contentType + "; boundary=" + m_boundary);
     }
 
     frameRequest.resourceRequest().setURL(requestURL());
     frameRequest.resourceRequest().addHTTPOriginIfNeeded(AtomicString(m_origin));
 }
 
 }