packed UI component don't tigger onMount life hooks

[cloudfroster]

Describe the bug
A clear and concise description of what the bug is.

when use packed UI component, the UI component's children component's onMount life hooks do
not tigger.

Logs
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To Reproduce
To help us help you, if you've found a bug please consider the following:
button.svelte

<div>button</div>

<script>
import { onMount } from 'svelte'

// [bug] don't tigger
onMount(() => {
  console.log('mount button')
})
</script>

red-button.svelte

<div>
  <Button></Button>
</div>

<script>
import { onMount } from 'svelte'

// will tigger
onMount(() => {
  console.log('mount red button')
})
</script>

index.js

import RedButton from './red-button.svelte'

export default RedButton

when use rollup to pack the RedButton to npm package. other user use the component,
the red component's button will not trigger onMount.

see source:

https://github.com/cloudfroster/svelte-build-component

git clone then npm install,just run npm run dev.

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Expected behavior
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Stacktraces
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Stack trace

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Information about your Svelte project:

• Your browser and the version: (e.x. Chrome 52.1, Firefox 48.0, IE 10)

• Your operating system: (e.x. OS X 10, Ubuntu Linux 19.10, Windows XP, etc)

• Svelte version (Please check you can reproduce the issue with the latest release!)

• Whether your project uses Webpack or Rollup

Severity
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Additional context
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[Conduitry]

This sounds like the issue that was being pursued in #3671 - that basically you shouldn't use a fully compiled and bundled Svelte component inside of another Svelte app because having two copies of Svelte's internal scheduler breaks things.

[cloudfroster]

node_modules package i use external svelte, the onMount will trigger ,but the call order is not correct.
it will call

mount F
mount E
mount app
mount B
mount C

expect order

mount B
mount C
mount F
mount E
mount app

you can reproduct in https://github.com/cloudfroster/svelte-build-component

[cloudfroster]

ok i fixed it, must external 'svelte/internal'.