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# Description

The Playground page does not render the "Hello World" example using Firefox 100.0 (64-bit) in macOS Big Sur. Reproducible with all addons disabled. Does it work correctly in Safari Version 14.1.2 (16611.3.10.1.6). Other browsers not checked.

# Steps to Reproduce

Open (https://lit.dev/playground/)[https://lit.dev/playground/]

2. See this output...

## Live Reproduction Link

https://lit-html.stackblitz.io/ stuck with "Starting dev server" and this code:

```typescript
// Import lit-html functions
import { html, render } from 'lit-html';

// Define a template function
const myTemplate = name =>
html`

Hello ${name}!

`;

// Render the template with some data
render(myTemplate('lit-html'), document.body);
```

## Actual Results


## Browsers Affected

- [ ] Chrome
- [X] Firefox
- [ ] Edge
- [ ] Safari 11
- [ ] Safari 10
- [ ] IE 11

Start by opening https://lit.dev/playground/ in Firefox 100 on macOS and compare the result with Safari, using the reported Hello World example and screenshot as the reference. Trace the playground rendering path from the page entry point; done means the Hello World Playground page renders correctly in Firefox.

Written by the indexing model from the issue text.