Make classes and structures in core/html fast-allocated.

Source/core/html/parser/HTMLTokenizer.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * 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:
  * 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
@@ skipping 104 matching lines @@
         DOCTYPESystemIdentifierSingleQuotedState,
         AfterDOCTYPESystemIdentifierState,
         BogusDOCTYPEState,
         CDATASectionState,
         // These CDATA states are not in the HTML5 spec, but we use them internally.
         CDATASectionRightSquareBracketState,
         CDATASectionDoubleRightSquareBracketState,
     };
 
     struct Checkpoint {
+        STACK_ALLOCATED();
         HTMLParserOptions options;
         State state;
         UChar additionalAllowedCharacter;
         bool skipNextNewLine;
         bool shouldAllowCDATA;
 
         Checkpoint()
             : options(0)
             , state()
             , additionalAllowedCharacter('\0')
@@ skipping 147 matching lines @@
     // token (e.g., when lexing script). We buffer the name of the end tag
     // token here so we remember it next time we re-enter the tokenizer.
     Vector<LChar, 32> m_bufferedEndTagName;
 
     HTMLParserOptions m_options;
 };
 
 }
 
 #endif