This fixes an issue with HTML tags inside the <script> tag.
Remex also doesn't throw errors on attributes like @click, although it
does mangle them when producing DOM. To work around this, don't use DOM
serialization for the template HTML, but parse everything again using a
Remex parse+serialize pipeline that extracts the template and
(optionally) removes comments and strips whitespace.
One important effect of this change is that we'll have to forbid
self-closing tags in Vue templates, because Remex doesn't handle those
correctly (or rather, handles them *too* correctly). But on the up side,
we can now allow shorthands for v-bind/v-on/v-slot again.
Bug: T253334
Bug: T255587
Depends-On: I2253a2317187fe0d781ba5bfefab95e0f97d0a80
Change-Id: Id9a9728b7163601cc60bc587be07b70977d41970
8c6c1c9adc