Fixed the behaviour of form submit to Firefox: form does not submit once it has been removed.

third_party/WebKit/Source/core/frame/UseCounter.h

 /*
  * Copyright (C) 2012 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:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 1149 matching lines @@
         MediaStreamConstraintsOldAndNew = 1389,
         V8ArrayProtectorDirtied = 1390,
         V8ArraySpeciesModified = 1391,
         V8ArrayPrototypeConstructorModified = 1392,
         V8ArrayInstanceProtoModified = 1393,
         V8ArrayInstanceConstructorModified = 1394,
         V8LegacyFunctionDeclaration = 1395,
         V8RegExpPrototypeSourceGetter = 1396,
         V8RegExpPrototypeOldFlagGetter = 1397,
         V8DecimalWithLeadingZeroInStrictMode = 1398,
-        FormSubmissionNotInDocumentTree = 1399,
         GetUserMediaPrefixed = 1400,
         GetUserMediaLegacy = 1401,
         GetUserMediaPromise = 1402,
         CSSFilterFunctionNoArguments = 1403,
         V8LegacyDateParser = 1404,
         OpenSearchInsecureOriginInsecureTarget = 1405,
         OpenSearchInsecureOriginSecureTarget = 1406,
         OpenSearchSecureOriginInsecureTarget = 1407,
         OpenSearchSecureOriginSecureTarget = 1408,
         RegisterProtocolHandlerSecureOrigin = 1409,
@@ skipping 207 matching lines @@
     friend class UseCounterTest;
     unsigned m_muteCount;
 
     CountBits m_countBits;
     BitVector m_CSSFeatureBits;
 };
 
 } // namespace blink
 
 #endif // UseCounter_h