TextDocumentParser::TextDocumentParser(HTMLDocument* document) : HTMLDocumentParser(document, false) , m_haveInsertedFakePreElement(false) { tokenizer()->setState(HTMLTokenizerState::PLAINTEXTState); } ^^^ This code sets state on the main thread tokenizer, not the background tokenizer. We probably should just make TextDocumentParser always use the main thread.
Makes sense.
*** This bug has been marked as a duplicate of bug 109240 ***