When adding [HTMLConstruct] to HTMLEmbedElement.idl, we get following crash
with LayoutTests/external/wpt/custom-elements/builtin-coverage.html

#
# Fatal error in ../../v8\src/api.h, line 354
# Debug check failed: that == nullptr || (*reinterpret_cast<v8::internal::Object* const*>(that))->IsJSReceiver().
#
Backtrace:
        base::debug::StackTrace::StackTrace [0x100B8838+104] (C:\src\w\cr\src\base\debug\stack_trace_win.cc:286)
        base::debug::StackTrace::StackTrace [0x100B73F3+35] (C:\src\w\cr\src\base\debug\stack_trace.cc:199)
        gin::`anonymous namespace'::PrintStackTrace [0x111D61BF+31] (C:\src\w\cr\src\gin\v8_platform.cc:30)
        V8_Fatal [0x2066AF8B+107] (C:\src\w\cr\src\v8\src\base\logging.cc:135)
        v8::base::`anonymous namespace'::DefaultDcheckHandler [0x2066ACF6+22]
        v8::Object::HasOwnProperty [0x112C6E16+342] (C:\src\w\cr\src\v8\src\api.cc:4857)
        blink::`anonymous namespace'::GetScriptableObjectProperty<blink::V8HTMLEmbedElement> [0x1279717D+541] (C:\src\w\cr\src\third_party\WebKit\Source\bindings\core\v8\custom\V8HTMLPlugInElementCustom.cpp:68)
        blink::V8HTMLEmbedElement::namedPropertyGetterCustom [0x12796F42+82] (C:\src\w\cr\src\third_party\WebKit\Source\bindings\core\v8\custom\V8HTMLPlugInElementCustom.cpp:125)
        blink::V8HTMLEmbedElement::namedPropertyGetterCallback [0x15274EC8+216] (C:\src\w\cr\src\out\debug\gen\blink\bindings\core\v8\V8HTMLEmbedElement.cpp:385)
        v8::internal::PropertyCallbackArguments::BasicCallNamedGetterCallback [0x11A83A18+392] (C:\src\w\cr\src\v8\src\api-arguments-inl.h:108)
        v8::internal::PropertyCallbackArguments::CallNamedGetter [0x11A836FD+237] (C:\src\w\cr\src\v8\src\api-arguments-inl.h:85)
        v8::internal::`anonymous namespace'::GetPropertyWithInterceptorInternal [0x11B9F0EE+366] (C:\src\w\cr\src\v8\src\objects.cc:1858)
        v8::internal::JSObject::GetPropertyWithInterceptor [0x11B9953C+60] (C:\src\w\cr\src\v8\src\objects.cc:15753)
        v8::internal::Object::GetProperty [0x11B98EDE+78] (C:\src\w\cr\src\v8\src\objects.cc:1124)
        v8::internal::LoadIC::Load [0x11A6A193+723] (C:\src\w\cr\src\v8\src\ic\ic.cc:461)
        v8::internal::__RT_impl_Runtime_LoadIC_Miss [0x11A79FD1+321] (C:\src\w\cr\src\v8\src\ic\ic.cc:2083)
        v8::internal::Runtime_LoadIC_Miss [0x11A79BF7+199] (C:\src\w\cr\src\v8\src\ic\ic.cc:2066)
Assertion failed: false, file ../../third_party/swiftshader/src/OpenGL/common/Object.cpp, line 96