Editorial: be a little clearer on HTMLCollection

Fixes #203.

dom.bs

@@ -2536,7 +2536,8 @@ interface HTMLCollection {
 <p>An {{HTMLCollection}} object is a <a>collection</a> of <a for="/">elements</a>.
 
 <p class="note no-backref">{{HTMLCollection}} is an historical artifact we cannot rid the web of.
-Please do not use it in new APIs.
+While developers are of course welcome to keep using it, new API standard designers ought not to use
+it (use <code>sequence&lt;T></code> in IDL instead).
 
 <dl class=domintro>
  <dt><var>collection</var> . {{HTMLCollection/length}}
@@ -9391,6 +9392,7 @@ Ryosuke Niwa,
 Sam Dutton,
 Samuel Giles,
 Sebastian Mayr,
+<i>senolv</i>,
 Seo Sanghyeon,
 Sergey G. Grekhov,
 Shiki Okasaka,

dom.html

@@ -1540,7 +1540,8 @@ <h5 class="heading settled" data-level="4.2.10.2" id="interface-htmlcollection">
 </pre>
    <p>An <code class="idl"><a data-link-type="idl" href="#htmlcollection">HTMLCollection</a></code> object is a <a data-link-type="dfn" href="#concept-collection">collection</a> of <a data-link-type="dfn" href="#concept-element">elements</a>. </p>
    <p class="note no-backref" role="note"><code class="idl"><a data-link-type="idl" href="#htmlcollection">HTMLCollection</a></code> is an historical artifact we cannot rid the web of.
-Please do not use it in new APIs. </p>
+While developers are of course welcome to keep using it, new API standard designers ought not to use
+it (use <code>sequence&lt;T></code> in IDL instead). </p>
    <dl class="domintro">
     <dt><var>collection</var> . <code class="idl"><a data-link-type="idl" href="#dom-htmlcollection-length">length</a></code> 
     <dd> Returns the number of <a data-link-type="dfn" href="#concept-element">elements</a> in
@@ -2427,7 +2428,7 @@ <h3 class="heading settled" data-level="4.5" id="interface-document"><span class
    <p>Unless stated otherwise, a <a data-link-type="dfn" href="#concept-document">document</a>’s <a data-link-type="dfn" href="#concept-document-base-url">base URL</a> is
 "<code>about:blank</code>", <a data-link-type="dfn" href="#concept-document-encoding">encoding</a> is the <a data-link-type="dfn" href="https://encoding.spec.whatwg.org/#utf-8">utf-8</a> <a data-link-type="dfn" href="https://encoding.spec.whatwg.org/#encoding">encoding</a>, <a data-link-type="dfn" href="#concept-document-content-type">content type</a> is
 "<code>application/xml</code>", <a data-link-type="dfn" href="#concept-document-url">URL</a> is "<code>about:blank</code>", <a data-link-type="dfn" href="#concept-document-type">type</a> is "<code>xml</code>", and its <a data-link-type="dfn" href="#concept-document-mode">mode</a> is "<code>no-quirks</code>".</p>
-   <p>Unless stated otherwise, a <a data-link-type="dfn" href="#concept-document">document</a>’s <a data-link-type="dfn" href="https://html.spec.whatwg.org/multipage/browsers.html#concept-origin">origin</a> is an <a data-link-type="dfn" href="https://html.spec.whatwg.org/multipage/browsers.html#concept-origin-opaque">opaque origin</a>. <a data-link-type="biblio" href="#biblio-html">[HTML]</a></p>
+   <p>Unless stated otherwise, a <a data-link-type="dfn" href="#concept-document">document</a>’s <a data-link-type="dfn" href="https://html.spec.whatwg.org/multipage/browsers.html#concept-origin">origin</a> is a new <a data-link-type="dfn" href="https://html.spec.whatwg.org/multipage/browsers.html#concept-origin-opaque">opaque origin</a>. <a data-link-type="biblio" href="#biblio-html">[HTML]</a></p>
    <p>A <a data-link-type="dfn" href="#concept-document">document</a> is said to be an <dfn data-dfn-type="dfn" data-export="" id="xml-document">XML document<a class="self-link" href="#xml-document"></a></dfn> if its <a data-link-type="dfn" href="#concept-document-type">type</a> is "<code>xml</code>", and an <dfn data-dfn-type="dfn" data-export="" id="html-document">HTML document<a class="self-link" href="#html-document"></a></dfn> otherwise. Whether a <a data-link-type="dfn" href="#concept-document">document</a> is an <a data-link-type="dfn" href="#html-document">HTML document</a> or an <a data-link-type="dfn" href="#xml-document">XML document</a> affects the behavior of certain APIs.</p>
    <p>A <a data-link-type="dfn" href="#concept-document">document</a> is said to be in <dfn data-dfn-type="dfn" data-export="" id="concept-document-no-quirks">no-quirks mode<a class="self-link" href="#concept-document-no-quirks"></a></dfn> if its <a data-link-type="dfn" href="#concept-document-mode">mode</a> is "<code>no-quirks</code>", <dfn data-dfn-type="dfn" data-export="" id="concept-document-quirks">quirks mode<a class="self-link" href="#concept-document-quirks"></a></dfn> if its <a data-link-type="dfn" href="#concept-document-mode">mode</a> is "<code>quirks</code>", and <dfn data-dfn-type="dfn" data-export="" id="concept-document-limited-quirks">limited-quirks mode<a class="self-link" href="#concept-document-limited-quirks"></a></dfn> if its <a data-link-type="dfn" href="#concept-document-mode">mode</a> is "<code>limited-quirks</code>".</p>
    <div class="note no-backref" role="note">
@@ -4827,7 +4828,7 @@ <h2 class="no-num heading settled" id="acks"><span class="content">Acknowledgmen
 Ryosuke Niwa,
 Sam Dutton,
 Samuel Giles,
-Sebastian Mayr,
+Sebastian Mayr, <i>senolv</i>,
 Seo Sanghyeon,
 Sergey G. Grekhov,
 Shiki Okasaka,