fix: When ce is used multiple times, subcomponents can mount the style

[baiwusanyu-c]

close: #49 Implementation code: https://github.com/baiwusanyu-c/bwsy-vue-core/commit/cd6877694ce9290a0b3cdf61020ee9562d4a5949 Relate PR: https://github.com/vuejs/core/pull/7942