delete useThreading flag as it is always true

Source/core/html/parser/HTMLTreeBuilder.cpp

Index: Source/core/html/parser/HTMLTreeBuilder.cpp
diff --git a/Source/core/html/parser/HTMLTreeBuilder.cpp b/Source/core/html/parser/HTMLTreeBuilder.cpp
index 41f8e1938079983b9ca999830e6c11a54e25afa2..eb7273080f60c8fc3cf1b8819eff8678505d68d8 100644
--- a/Source/core/html/parser/HTMLTreeBuilder.cpp
+++ b/Source/core/html/parser/HTMLTreeBuilder.cpp
@@ -2113,7 +2113,6 @@ void HTMLTreeBuilder::processEndTag(AtomicHTMLToken* token)
             if (m_parser->tokenizer()) {
                 // We must set the tokenizer's state to
                 // DataState explicitly if the tokenizer didn't have a chance to.
-                ASSERT(m_parser->tokenizer()->state() == HTMLTokenizer::DataState || m_options.useThreading);
                 m_parser->tokenizer()->setState(HTMLTokenizer::DataState);
             }
             return;