Import upstream changes (da9db86a33cba710d439e254df2492f9f6dcbbee)

.gitignore

@@ -7,3 +7,5 @@ my-element.js
 my-element.js.map
 my-element.d.ts
 my-element.d.ts.map
+# only generated for size check
+my-element.bundled.js

README.md

@@ -35,8 +35,7 @@ Both the TypeScript compiler and lit-analyzer are configured to be very strict.
 ## Testing
 
 This sample uses modern-web.dev's
-[@web/test-runner](https://www.npmjs.com/package/@web/test-runner) along with
-Mocha, Chai, and some related helpers for testing. See the
+[@web/test-runner](https://www.npmjs.com/package/@web/test-runner) for testing. See the
 [modern-web.dev testing documentation](https://modern-web.dev/docs/test-runner/overview) for
 more information.
 

docs/install/index.html

@@ -34,7 +34,7 @@ <h2>Local Installation</h2>
 <pre class="language-bash"><code class="language-bash"><span class="token function">npm</span> i my-element</code></pre>
 <h2>CDN</h2>
 <p>npm CDNs like <a href="">unpkg.com</a> can directly serve files that have been published to npm. This works great for standard JavaScript modules that the browser can load natively.</p>
-<p>For this element to work from unpkg.com specifically, you need to include the <code>?module</code> query parameter, which tells unpkg.com to rewrite &quot;bare&quot; module specificers to full URLs.</p>
+<p>For this element to work from unpkg.com specifically, you need to include the <code>?module</code> query parameter, which tells unpkg.com to rewrite &quot;bare&quot; module specifiers to full URLs.</p>
 <h3>HTML</h3>
 <pre class="language-html"><code class="language-html"><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;</span>script</span> <span class="token attr-name">type</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>module<span class="token punctuation">"</span></span> <span class="token attr-name">src</span><span class="token attr-value"><span class="token punctuation attr-equals">=</span><span class="token punctuation">"</span>https://unpkg.com/my-element?module<span class="token punctuation">"</span></span><span class="token punctuation">></span></span><span class="token script"></span><span class="token tag"><span class="token tag"><span class="token punctuation">&lt;/</span>script</span><span class="token punctuation">></span></span></code></pre>
 <h3>JavaScript</h3>