The HTML parser synchronously creates custom elements

third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h

Index: third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h
diff --git a/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h b/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h
index e83f3bbd6411bb80acc842efc99330e4db6cc7de..4d5873ce0ed025e0ae55059baaae8ab88be5e2e6 100644
--- a/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h
+++ b/third_party/WebKit/Source/core/html/parser/HTMLDocumentParser.h
@@ -35,6 +35,7 @@
 #include "core/html/parser/CompactHTMLToken.h"
 #include "core/html/parser/HTMLInputStream.h"
 #include "core/html/parser/HTMLParserOptions.h"
+#include "core/html/parser/HTMLParserReentryPermit.h"
 #include "core/html/parser/HTMLPreloadScanner.h"
 #include "core/html/parser/HTMLScriptRunnerHost.h"
 #include "core/html/parser/HTMLSourceTracker.h"
@@ -95,6 +96,8 @@ public:
     void suspendScheduledTasks() final;
     void resumeScheduledTasks() final;
 
+    HTMLParserReentryPermit* reentryPermit() { return m_reentryPermit; }
+
     struct TokenizedChunk {
         USING_FAST_MALLOC(TokenizedChunk);
     public:
@@ -204,6 +207,7 @@ private:
 
     HTMLParserOptions m_options;
     HTMLInputStream m_input;
+    Member<HTMLParserReentryPermit> m_reentryPermit;
 
     std::unique_ptr<HTMLToken> m_token;
     std::unique_ptr<HTMLTokenizer> m_tokenizer;