Add new tests for customelementregistry content attribute and specifying null to createEleent and attachShadow per#56108

rniwa merged 1 commit into

web-platform-tests:masterweb-platform-tests/wpt:masterfrom

rniwa:add-scoped-custom-element-registry-customelementregistry-attributerniwa/web-platform-tests:add-scoped-custom-element-registry-customelementregistry-attributeCopy head branch name to clipboard