fix(hydration): should force hydrate props with .prop & .attr modifiers

[edison1105]

related to #7476
NOTE:
This PR does not fundamentally solve the problem; it simply aligns with the behavior of Vue 2.
see #7490 (comment)

[github-actions]

Size Report

Bundles

File	Size	Gzip	Brotli
runtime-dom.global.prod.js	85.9 kB (+24 B)	32.7 kB (+8 B)	29.5 kB (+33 B)
vue.global.prod.js	132 kB (+24 B)	49.4 kB (+10 B)	44.3 kB (-49 B)

Usages

Name	Size	Gzip	Brotli
createApp	47.9 kB	18.8 kB	17.2 kB (-2 B)
createSSRApp	50.7 kB (+24 B)	20 kB (+8 B)	18.2 kB (-1 B)
defineCustomElement	50.3 kB	19.6 kB (-1 B)	17.9 kB (+1 B)
overall	61.2 kB	23.7 kB	21.6 kB

[skirtles-code]

I have a few questions about this change.

1. Why do we need to force the patching of props that use .attr? Won't those be the same as what's in the SSR HTML anyway?
2. Does this really close static non-attr bindings does not work in SSR #7476? I can see how this change would be helpful in the scenario described there, but I'm not sure whether it fully addresses the problem.
3. As a potential follow up to this change, currently props marked with .prop are still rendered as attributes in the SSR HTML. Do you think it would be better to omit them from the HTML entirely and just set them as part of hydration?

[edison1105]

@skirtles-code
Actually, the problem is not fundamentally solved. A better solution would be to output a js code on the SSR to set the indeterminate property. However, it seems that SSR currently lacks this capability. In Vue 2, we could modify the checkbox state during the hydration phase using :indeterminate.prop, but this doesn't work in Vue 3. This PR aims to maintain the same behavior as Vue 2.

see vuejs/vue#4094 (comment)

[yyx990803]

#7476 really is more of a specific case for indeterminate since <input type="checkbox" indeterminate> works in CSR due to the runtime patchProps logic, so we have to special case it to make it consistent in SSR. This is done in 34b5a5d

The intention of this PR makes sense, but there are two problems:

1. .attr modifier should not require forced hydration since it would have already been rendered by the server. The only required case is .prop.
2. v-bind with .prop modifier is not guaranteed to enter the branch being modified here. We need to update the compiler so that elements with v-bind.prop are marked with a patch flag that makes it enter this branch.

See 364f319

With both commits all variations of indeterminate bindings should work properly in hydration: https://play.vuejs.org/#__SSR__eNqVUk1LAzEQ/StjLqsg20Nvy1ZQKagHFRW85FJ3p2tqvkgmtVL2vzub0qqgVW/JvDdv3jxmLU69L5cJRSXq2ATlCSJS8ifSKuNdIFhDwDn0MA/OQMHUQlppG2cjgYkdTAb8sLhArR08uqDbg+JI2nq0kWMh/hAar2eE/AOolfWJgN48TqRonrF5eXIrKUDZFgmDUfZXavWFyxiFhFL8p6n0wfk/dpY/jqtHu93EsaDIwcxVVy6is5zpelBlJWe80hhuPCkOTooKMjJgM87t9SrXBtHjbT1P/6a+iGyo4sdtwIhhyTZ2GM1Ch7SBp/fXuOL3DjSuTZrZe8A7jE6nweOGdpZsy7Y/8bLby3wZynYPcboitHG7VE6FmX3mS8HXcr5n9Q+743Kc+6TtRf8OSHfgNQ==