Define 'max length' and 'max duration' normatively

Mitigates fingerprinting and tracking vectors that rely on
inconsistencies across devices per W3C Security review
recommendation:

w3c/security-request#71

Note: max duration is expressed in milliseconds.

index.html

@@ -144,8 +144,7 @@ <h2>
             </li>
           </ol>
         </li>
-        <li>Let <var>max length</var> be an implementation-dependent maximum
-        length of <var>pattern</var>.
+        <li>Let <var>max length</var> have the value 10.
           <div class='note'>
             If the length of a pattern is greater than max length an
             implementation of this API could consider breaking the request
@@ -170,8 +169,7 @@ <h2>
             point.
           </div>
         </li>
-        <li>Let <var>max duration</var> be an implementation-dependent maximum
-        duration for a single vibration entry in a <var>pattern</var>.
+        <li>Let <var>max duration</var> have the value 10000.
         </li>
         <li>For each entry in <var>pattern</var> whose value is greater than
         <var>max duration</var>, set the entry's value to <var>max