Inconsistent boolean element property processing

Describe the bug

I noticed that Svelte changes my html slightly during rendering when boolean HTML attributes are in use.

Here's a two lines of HTML from a svelte file:

<form action="#" novalidate></form>
<custom-element popover></custom-element>

Here's how it's rendered:

<form action="#" novalidate></form> 
<custom-element popover=""></custom-element>

Note how the popover attribute was unexpectedly altered into a string while novalidate was not.

Reproduction

Drop these lines into any *.svelte file and observe the rendered source.

<form action="#" novalidate></form>
<custom-element popover></custom-element>

Logs

System Info

System:
    OS: Linux 6.8 Linux Mint 22 (Wilma)
    CPU: (16) x64 AMD Ryzen 7 5700G with Radeon Graphics
    Memory: 16.49 GB / 30.72 GB
    Container: Yes
    Shell: 5.2.21 - /bin/bash
  Binaries:
    Node: 20.19.4 - ~/.bin/node/bin/node
    npm: 10.8.2 - ~/.bin/node/bin/npm
  Browsers:
    Chrome: 139.0.7258.154
  npmPackages:
    @sveltejs/adapter-auto: ^6.0.0 => 6.1.0 
    @sveltejs/kit: ^2.22.0 => 2.37.0 
    @sveltejs/vite-plugin-svelte: ^6.0.0 => 6.1.3 
    svelte: ^5.0.0 => 5.38.6 
    vite: ^7.0.4 => 7.1.4

Severity

annoyance

Additional Information

No response

Start with the reported reproduction in any *.svelte file and compare the rendered source for the novalidate and popover attributes. Trace how these boolean HTML attributes are processed, then verify that both attributes are rendered consistently without changing their intended form.