fix(v-pre): skip compiling custom component tags in v-pre blocks (fix…

[haoqunjiang]

… #8286)

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• Bugfix
• Feature
• Code style update
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Other information:

Turns out to be an easy fix…
Never thought the root cause could be in codegen and wasted a lot of time diving into vdom 😂.

A side effect of this fix is that every descendent component in a v-pre block would also carry a { pre: true } property.

[tyurderi]

c'mon approve and merge this fix please 😄