Always preload all tokens before parsing

Source/core/html/parser/HTMLDocumentParser.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:
  * 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 337 matching lines @@
         m_preloader->takeAndPreload(chunk->preloads);
         m_speculations.append(chunk);
         return;
     }
 
     // processParsedChunkFromBackgroundParser can cause this parser to be detached from the Document,
     // but we need to ensure it isn't deleted yet.
     RefPtrWillBeRawPtr<HTMLDocumentParser> protect(this);
 
     ASSERT(m_speculations.isEmpty());
-    chunk->preloads.clear(); // We don't need to preload because we're going to parse immediately.
+    // This preload call is redundant, but we plan to change treebuilding to
+    // always operate asynchronously after a message-loop round trip after delivery
+    // to the main thread, thus we'll always use the preloader. Before making
+    // that change, we're sending all chunks through the preloader right
+    // before treebuilding (changes 15 layout tests).
+    // https://codereview.chromium.org/258013009/
+    m_preloader->takeAndPreload(chunk->preloads);
     m_speculations.append(chunk);
     pumpPendingSpeculations();
 }
 
 void HTMLDocumentParser::didReceiveEncodingDataFromBackgroundParser(const DocumentEncodingData& data)
 {
     document()->setEncodingData(data);
 }
 
 void HTMLDocumentParser::validateSpeculations(PassOwnPtr<ParsedChunk> chunk)
@@ skipping 687 matching lines @@
 void HTMLDocumentParser::setDecoder(PassOwnPtr<TextResourceDecoder> decoder)
 {
     ASSERT(decoder);
     DecodedDataDocumentParser::setDecoder(decoder);
 
     if (m_haveBackgroundParser)
         HTMLParserThread::shared()->postTask(bind(&BackgroundHTMLParser::setDecoder, m_backgroundParser, takeDecoder()));
 }
 
 }