Always preload all tokens before parsing

Source/core/html/parser/HTMLDocumentParser.cpp

Index: Source/core/html/parser/HTMLDocumentParser.cpp
diff --git a/Source/core/html/parser/HTMLDocumentParser.cpp b/Source/core/html/parser/HTMLDocumentParser.cpp
index eb350704d72e29f89c37522f65c2a5986da5d389..ba498efba2f7ba1e5dfbeec1d16c9fc1eaa5283c 100644
--- a/Source/core/html/parser/HTMLDocumentParser.cpp
+++ b/Source/core/html/parser/HTMLDocumentParser.cpp
@@ -355,7 +355,13 @@ void HTMLDocumentParser::didReceiveParsedChunkFromBackgroundParser(PassOwnPtr<Pa
     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();
 }