Editorial: define defaults for EventListenerOptions

Although this is also done in prose, this nonetheless simplifies the
prose a bit and makes it clearer to those skimming the standard what is
going on (although skimming is not recommended).

Fixes #239.

Author: annevk

dom.bs

@@ -951,12 +951,12 @@ callback interface EventListener {
 };
 
 dictionary EventListenerOptions {
-  boolean capture;
+  boolean capture = false;
 };
 
 dictionary AddEventListenerOptions : EventListenerOptions {
-  boolean passive;
-  boolean once;
+  boolean passive = false;
+  boolean once = false;
 };
 </pre>
 
@@ -1039,8 +1039,8 @@ steps:
 
  <li><p>If <var>options</var> is a boolean, set <var>capture</var> to <var>options</var>.
 
- <li><p>If <var>options</var> is a dictionary and <code>{{EventListenerOptions/capture}}</code> is
- present in <var>options</var> with value true, then set <var>capture</var> to true.
+ <li><p>If <var>options</var> is a dictionary, then set <var>capture</var> to <var>options</var>'s
+ <code>{{EventListenerOptions/capture}}</code>.
 
  <li><p>Return <var>capture</var>.
 </ol>
@@ -1053,11 +1053,9 @@ steps:
 
  <li><p>Let <var>once</var> and <var>passive</var> be false.
 
- <li><p>If <var>options</var> is a dictionary and <code>{{AddEventListenerOptions/passive}}</code>
- is present in <var>options</var> with value true, then set <var>passive</var> to true.
-
- <li><p>If <var>options</var> is a dictionary and <code>{{AddEventListenerOptions/once}}</code> is
- present in <var>options</var> with value true, then set <var>once</var> to true.
+ <li><p>If <var>options</var> is a dictionary, then set <var>passive</var> to <var>options</var>'s
+ <code>{{AddEventListenerOptions/passive}}</code> and <var>once</var> to <var>options</var>'s
+ <code>{{AddEventListenerOptions/once}}</code>.
 
  <li><p>Return <var>capture</var>, <var>passive</var>, and <var>once</var>.
 </ol>

dom.html

@@ -705,12 +705,12 @@ <h3 class="heading settled" data-level="3.6" id="interface-eventtarget"><span cl
 };
 
 dictionary <dfn class="idl-code" data-dfn-type="dictionary" data-export="" id="dictdef-eventlisteneroptions">EventListenerOptions<a class="self-link" href="#dictdef-eventlisteneroptions"></a></dfn> {
-  boolean <dfn class="idl-code" data-dfn-for="EventListenerOptions" data-dfn-type="dict-member" data-export="" data-type="boolean " id="dom-eventlisteneroptions-capture">capture<a class="self-link" href="#dom-eventlisteneroptions-capture"></a></dfn>;
+  boolean <dfn class="idl-code" data-default="false" data-dfn-for="EventListenerOptions" data-dfn-type="dict-member" data-export="" data-type="boolean " id="dom-eventlisteneroptions-capture">capture<a class="self-link" href="#dom-eventlisteneroptions-capture"></a></dfn> = false;
 };
 
 dictionary <dfn class="idl-code" data-dfn-type="dictionary" data-export="" id="dictdef-addeventlisteneroptions">AddEventListenerOptions<a class="self-link" href="#dictdef-addeventlisteneroptions"></a></dfn> : <a data-link-type="idl-name" href="#dictdef-eventlisteneroptions">EventListenerOptions</a> {
-  boolean <dfn class="idl-code" data-dfn-for="AddEventListenerOptions" data-dfn-type="dict-member" data-export="" data-type="boolean " id="dom-addeventlisteneroptions-passive">passive<a class="self-link" href="#dom-addeventlisteneroptions-passive"></a></dfn>;
-  boolean <dfn class="idl-code" data-dfn-for="AddEventListenerOptions" data-dfn-type="dict-member" data-export="" data-type="boolean " id="dom-addeventlisteneroptions-once">once<a class="self-link" href="#dom-addeventlisteneroptions-once"></a></dfn>;
+  boolean <dfn class="idl-code" data-default="false" data-dfn-for="AddEventListenerOptions" data-dfn-type="dict-member" data-export="" data-type="boolean " id="dom-addeventlisteneroptions-passive">passive<a class="self-link" href="#dom-addeventlisteneroptions-passive"></a></dfn> = false;
+  boolean <dfn class="idl-code" data-default="false" data-dfn-for="AddEventListenerOptions" data-dfn-type="dict-member" data-export="" data-type="boolean " id="dom-addeventlisteneroptions-once">once<a class="self-link" href="#dom-addeventlisteneroptions-once"></a></dfn> = false;
 };
 </pre>
    <p>The <code class="idl"><a data-link-type="idl" href="#eventtarget">EventTarget</a></code> object represents the target to which an <a data-link-type="dfn" href="#concept-event">event</a> is <a data-link-type="dfn" href="#concept-event-dispatch">dispatched</a> when something has occurred. </p>
@@ -760,8 +760,7 @@ <h3 class="heading settled" data-level="3.6" id="interface-eventtarget"><span cl
     <li>
      <p>If <var>options</var> is a boolean, set <var>capture</var> to <var>options</var>. </p>
     <li>
-     <p>If <var>options</var> is a dictionary and <code><code class="idl"><a data-link-type="idl" href="#dom-eventlisteneroptions-capture">capture</a></code></code> is
- present in <var>options</var> with value true, then set <var>capture</var> to true. </p>
+     <p>If <var>options</var> is a dictionary, then set <var>capture</var> to <var>options</var>’s <code><code class="idl"><a data-link-type="idl" href="#dom-eventlisteneroptions-capture">capture</a></code></code>. </p>
     <li>
      <p>Return <var>capture</var>. </p>
    </ol>
@@ -773,10 +772,7 @@ <h3 class="heading settled" data-level="3.6" id="interface-eventtarget"><span cl
     <li>
      <p>Let <var>once</var> and <var>passive</var> be false. </p>
     <li>
-     <p>If <var>options</var> is a dictionary and <code><code class="idl"><a data-link-type="idl" href="#dom-addeventlisteneroptions-passive">passive</a></code></code> is present in <var>options</var> with value true, then set <var>passive</var> to true. </p>
-    <li>
-     <p>If <var>options</var> is a dictionary and <code><code class="idl"><a data-link-type="idl" href="#dom-addeventlisteneroptions-once">once</a></code></code> is
- present in <var>options</var> with value true, then set <var>once</var> to true. </p>
+     <p>If <var>options</var> is a dictionary, then set <var>passive</var> to <var>options</var>’s <code><code class="idl"><a data-link-type="idl" href="#dom-addeventlisteneroptions-passive">passive</a></code></code> and <var>once</var> to <var>options</var>’s <code><code class="idl"><a data-link-type="idl" href="#dom-addeventlisteneroptions-once">once</a></code></code>. </p>
     <li>
      <p>Return <var>capture</var>, <var>passive</var>, and <var>once</var>. </p>
    </ol>
@@ -6406,12 +6402,12 @@ <h2 class="no-num no-ref heading settled" id="idl-index"><span class="content">I
 };
 
 dictionary <a href="#dictdef-eventlisteneroptions">EventListenerOptions</a> {
-  boolean <a data-type="boolean " href="#dom-eventlisteneroptions-capture">capture</a>;
+  boolean <a data-default="false" data-type="boolean " href="#dom-eventlisteneroptions-capture">capture</a> = false;
 };
 
 dictionary <a href="#dictdef-addeventlisteneroptions">AddEventListenerOptions</a> : <a data-link-type="idl-name" href="#dictdef-eventlisteneroptions">EventListenerOptions</a> {
-  boolean <a data-type="boolean " href="#dom-addeventlisteneroptions-passive">passive</a>;
-  boolean <a data-type="boolean " href="#dom-addeventlisteneroptions-once">once</a>;
+  boolean <a data-default="false" data-type="boolean " href="#dom-addeventlisteneroptions-passive">passive</a> = false;
+  boolean <a data-default="false" data-type="boolean " href="#dom-addeventlisteneroptions-once">once</a> = false;
 };
 
 [NoInterfaceObject,