The HTML parser synchronously creates custom elements

third_party/WebKit/Source/core/core.gypi

 {
     'includes': [
         'core_generated.gypi',
     ],
     'variables': {
         # Files for which bindings (.cpp and .h files) will be generated
         'core_idl_files': [
             'animation/KeyframeEffect.idl',
             'animation/AnimationEffectReadOnly.idl',
             'animation/AnimationEffectTiming.idl',
@@ skipping 3249 matching lines @@
             'html/parser/HTMLEntitySearch.h',
             'html/parser/HTMLEntityTable.h',
             'html/parser/HTMLFormattingElementList.cpp',
             'html/parser/HTMLFormattingElementList.h',
             'html/parser/HTMLInputStream.h',
             'html/parser/HTMLMetaCharsetParser.cpp',
             'html/parser/HTMLMetaCharsetParser.h',
             'html/parser/HTMLParserIdioms.cpp',
             'html/parser/HTMLParserOptions.cpp',
             'html/parser/HTMLParserOptions.h',
+            'html/parser/HTMLParserReentryPermit.cpp',
+            'html/parser/HTMLParserReentryPermit.h',
             'html/parser/HTMLParserScheduler.cpp',
             'html/parser/HTMLParserScheduler.h',
             'html/parser/HTMLParserThread.cpp',
             'html/parser/HTMLParserThread.h',
             'html/parser/HTMLPreloadScanner.cpp',
             'html/parser/HTMLPreloadScanner.h',
             'html/parser/HTMLResourcePreloader.cpp',
             'html/parser/HTMLResourcePreloader.h',
             'html/parser/HTMLScriptRunner.cpp',
             'html/parser/HTMLScriptRunner.h',
@@ skipping 993 matching lines @@
             'testing/PrivateScriptTestTest.cpp',
             'timing/MemoryInfoTest.cpp',
             'timing/PerformanceBaseTest.cpp',
             'timing/PerformanceObserverTest.cpp',
             'workers/WorkerThreadTest.cpp',
             'workers/WorkerThreadTestHelper.h',
             'xml/parser/SharedBufferReaderTest.cpp',
         ],
     }
 }