What are the new NodeExist.Definitely and NodeExist.Probably values for? When are we saying something 'probably' matches, and what do we do in that situation?

ok the gist of what I'm trying to do here is that, for example:

<div id="a" />
<div id="b" />

{#each foo}
   <div id="c" />
{/each}

<div id="d" />

#d tries to find it's siblings iteratively through element.prev.
in this case, it gets {#each} block and it has #c, which probably exist (NodeExist.Probably), because it's in an each block.
so i continue search it's sibling iteratively, and the next element is #b. #b definitely exists. (NodeExist.Definitely)
so i stop the search.

so both #b + #d and #c + #d will be marked as match, but not #a + #d

however, for another example:

<div id="a" />

{#each foo}
   <div id="b" />
{:else}
   <div id="c" />
{/each}

<div id="d" />

#d tries to find it's siblings.
in this case, {#each} block contains either #b or #c. but they definitely exists, one or the other.
so i stop the search.

so both #b + #d and #c + #d will be marked as match, but not #a + #d

i've tried to come up with test cases with different nested logic blocks:

{#each foo}
   {#if bar}
       <div id="a"/>
   {/if}
{:else}
   <div id="b" />
{/if}

here #a and #b is probably exist.

hopefully im able to cover all of the edge cases 😅

@tanhauhau Hi, this PR broke selectors like this one:

:global(*) + .button.margin {
  margin-top: 8px;
}

They are getting stripped despite global. I used them in Button, Input and Checkbox components.
Can you fix it?

Repro:

https://svelte.dev/repl/5ec4d420b4b44ea4b441da24010d8acd?version=3.26.0
https://svelte.dev/repl/5ec4d420b4b44ea4b441da24010d8acd?version=3.29.4