fix: fix hot-reload not working after options get modified

[liximomo]

Steps to reproduce:

1. clone this repo, start it in development mode.
2. change data msg in src/app.vue, hot reload works fine.
3. activate Vue Devtools panel in Chrome Devtools.
4. change data msg in src/app.vue, hot reload works fine.
5. change data msg in src/app.vue again, hot reload stop working.

What happened here?
Vue Devtools will patch the existed component options when it gets activated, which caused this line to be run. As a result, record.options._Ctor is now pointing to newCtor.options._Ctor, which breaks the connection between record.Ctor and record.options and cause hot-reload failure.

[sodatea]

This change looks good to me.
Amazing job on spotting such a hard-to-locate issue 👍