Multiline class attribute value breaks svelte

[kreativ-los]

Describe the bug
At my team we spread classes into multiple lines when there are more than two classes to make it more readable. This breaks svelte.

<div
  class="
    foo
  "
>
</div>

<style>
  .foo {
    background: red;
  }
</style>

Logs

ERROR in ./src/_components/Foo.svelte
Module Error (from ./node_modules/eslint-loader/dist/cjs.js):

[...]/_components/Foo.svelte
  9:3  warning  Unused CSS selector  css-unused-selector

To Reproduce
To reproduce just spread the classes named in the value of the class attribute into multiple lines, like in this REPL https://svelte.dev/repl/b85c17a37a0547f58f1bd221ae4bd8bc?version=3.16.7

<div
  class="
    foo
  "
>
</div>

<style>
  .foo {
    background: red;
  }
</style>

Expected behavior
Components are working as classes weren't written in multiple lines.

[ghost]

This look real similar to #4240

[Conduitry]

This was broken by me in #3552. Fix coming shortly.

[Conduitry]

Fixed in 3.17.2 - https://svelte.dev/repl/b85c17a37a0547f58f1bd221ae4bd8bc?version=3.17.2