Fix #93: use less loops

This changes the exception order for DOMTokenList’s add() and remove(),
but this is in line with implementations so all is good.

dom.bs

@@ -8770,10 +8770,15 @@ invoked, must run these steps:
 method, when invoked, must run these steps:
 
 <ol>
- <li><p>If one of <var>tokens</var> is the empty string, <a>throw</a> a {{SyntaxError}} exception.
+ <li>
+  <p>For each <var>token</var> in <var>tokens</var>, run these substeps:
 
- <li><p>If one of <var>tokens</var> contains any <a>ASCII whitespace</a>, then <a>throw</a> an
- {{InvalidCharacterError}} exception.
+  <ol>
+   <li><p>If <var>token</var> is the empty string, <a>throw</a> a {{SyntaxError}} exception.
+
+   <li><p>If <var>token</var> contains any <a>ASCII whitespace</a>, <a>throw</a> an
+   {{InvalidCharacterError}} exception.
+  </ol>
 
  <li>Let <var>valid</var> be true.
 
@@ -8791,10 +8796,15 @@ method, when invoked, must run these steps:
 method, when invoked, must run these steps:
 
 <ol>
- <li><p>If one of <var>tokens</var> is the empty string, <a>throw</a> a {{SyntaxError}} exception.
+ <li>
+  <p>For each <var>token</var> in <var>tokens</var>, run these substeps:
 
- <li><p>If one of <var>tokens</var> contains any <a>ASCII whitespace</a>, then <a>throw</a> an
- {{InvalidCharacterError}} exception.
+  <ol>
+   <li><p>If <var>token</var> is the empty string, <a>throw</a> a {{SyntaxError}} exception.
+
+   <li><p>If <var>token</var> contains any <a>ASCII whitespace</a>, <a>throw</a> an
+   {{InvalidCharacterError}} exception.
+  </ol>
 
  <li><p>For each <var>token</var> in <var>tokens</var>, remove <var>token</var> from <a>tokens</a>.
 

dom.html

@@ -4107,9 +4107,13 @@ <h3 class="heading settled" data-level="7.1" id="interface-domtokenlist"><span c
    <p>The <dfn class="idl-code" data-dfn-for="DOMTokenList" data-dfn-type="method" data-export="" data-lt="add(tokens)|add()" id="dom-domtokenlist-add"><code>add(<var>tokens</var>…)</code><a class="self-link" href="#dom-domtokenlist-add"></a></dfn> method, when invoked, must run these steps: </p>
    <ol>
     <li>
-     <p>If one of <var>tokens</var> is the empty string, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-throw">throw</a> a <code class="idl"><a data-link-type="idl" href="https://heycam.github.io/webidl/#syntaxerror">SyntaxError</a></code> exception. </p>
-    <li>
-     <p>If one of <var>tokens</var> contains any <a data-link-type="dfn" href="https://encoding.spec.whatwg.org/#ascii-whitespace">ASCII whitespace</a>, then <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-throw">throw</a> an <code class="idl"><a data-link-type="idl" href="https://heycam.github.io/webidl/#invalidcharactererror">InvalidCharacterError</a></code> exception. </p>
+     <p>For each <var>token</var> in <var>tokens</var>, run these substeps: </p>
+     <ol>
+      <li>
+       <p>If <var>token</var> is the empty string, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-throw">throw</a> a <code class="idl"><a data-link-type="idl" href="https://heycam.github.io/webidl/#syntaxerror">SyntaxError</a></code> exception. </p>
+      <li>
+       <p>If <var>token</var> contains any <a data-link-type="dfn" href="https://encoding.spec.whatwg.org/#ascii-whitespace">ASCII whitespace</a>, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-throw">throw</a> an <code class="idl"><a data-link-type="idl" href="https://heycam.github.io/webidl/#invalidcharactererror">InvalidCharacterError</a></code> exception. </p>
+     </ol>
     <li>Let <var>valid</var> be true. 
     <li>
      <p>For each <var>token</var> in <var>tokens</var>, in given order, that is not in <a data-link-type="dfn" href="#concept-dtl-tokens">tokens</a>, run <a data-link-type="dfn" href="#concept-domtokenlist-validation">validation steps</a> with <var>token</var>. If the return value is false,
@@ -4122,9 +4126,13 @@ <h3 class="heading settled" data-level="7.1" id="interface-domtokenlist"><span c
    <p>The <dfn class="idl-code" data-dfn-for="DOMTokenList" data-dfn-type="method" data-export="" data-lt="remove(tokens)|remove()" id="dom-domtokenlist-remove"><code>remove(<var>tokens</var>…)</code><a class="self-link" href="#dom-domtokenlist-remove"></a></dfn> method, when invoked, must run these steps: </p>
    <ol>
     <li>
-     <p>If one of <var>tokens</var> is the empty string, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-throw">throw</a> a <code class="idl"><a data-link-type="idl" href="https://heycam.github.io/webidl/#syntaxerror">SyntaxError</a></code> exception. </p>
-    <li>
-     <p>If one of <var>tokens</var> contains any <a data-link-type="dfn" href="https://encoding.spec.whatwg.org/#ascii-whitespace">ASCII whitespace</a>, then <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-throw">throw</a> an <code class="idl"><a data-link-type="idl" href="https://heycam.github.io/webidl/#invalidcharactererror">InvalidCharacterError</a></code> exception. </p>
+     <p>For each <var>token</var> in <var>tokens</var>, run these substeps: </p>
+     <ol>
+      <li>
+       <p>If <var>token</var> is the empty string, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-throw">throw</a> a <code class="idl"><a data-link-type="idl" href="https://heycam.github.io/webidl/#syntaxerror">SyntaxError</a></code> exception. </p>
+      <li>
+       <p>If <var>token</var> contains any <a data-link-type="dfn" href="https://encoding.spec.whatwg.org/#ascii-whitespace">ASCII whitespace</a>, <a data-link-type="dfn" href="https://heycam.github.io/webidl/#dfn-throw">throw</a> an <code class="idl"><a data-link-type="idl" href="https://heycam.github.io/webidl/#invalidcharactererror">InvalidCharacterError</a></code> exception. </p>
+     </ol>
     <li>
      <p>For each <var>token</var> in <var>tokens</var>, remove <var>token</var> from <a data-link-type="dfn" href="#concept-dtl-tokens">tokens</a>. </p>
     <li>