Fix and clarify more around CDATASection

 * Make appendChild(cdata) and similar not throw.
 * Let nodeName be #cdata-section.
 * Include CDATASection as a node in an exhaustive enumeration.
 * Collapse cases of Text+PI+Comment to CharacterData where possible
   so that it's more clear that subtypes are included.
 * Say "depending on" instead of "switched" on.

Part of #300.

Author: foolip

dom.bs

@@ -1488,7 +1488,7 @@ can be used to explore this matter in more detail.
 
 <h3 id=node-trees>Node tree</h3>
 
-<p>{{Document}}, {{DocumentType}}, {{DocumentFragment}}, {{Element}}, {{Text}},
+<p>{{Document}}, {{DocumentType}}, {{DocumentFragment}}, {{Element}}, {{Text}}, {{CDATASection}},
 {{ProcessingInstruction}}, and {{Comment}} objects (simply called
 <dfn export id=concept-node>nodes</dfn>) <a>participate</a> in a <a>tree</a>, simply named the
 <dfn export id=concept-node-tree>node tree</dfn>.
@@ -1509,10 +1509,11 @@ can be used to explore this matter in more detail.
   </ol>
  <dt>{{DocumentFragment}}
  <dt>{{Element}}
- <dd><p>Zero or more nodes each of which is {{Element}}, {{Text}}, {{ProcessingInstruction}}, or
- {{Comment}}.
+ <dd><p>Zero or more nodes each of which is {{Element}}, {{Text}}, {{CDATASection}},
+ {{ProcessingInstruction}}, or {{Comment}}.
  <dt>{{DocumentType}}
  <dt>{{Text}}
+ <dt>{{CDATASection}}
  <dt>{{ProcessingInstruction}}
  <dt>{{Comment}}
  <dd><p>None.
@@ -1526,9 +1527,7 @@ The <dfn export id=concept-node-length for=Node>length</dfn> of a
  <dt>{{DocumentType}}
  <dd>Zero.
 
- <dt>{{Text}}
- <dt>{{ProcessingInstruction}}
- <dt>{{Comment}}
+ <dt>{{CharacterData}}
  <dd>Its {{CharacterData/length}} attribute
  value.
 
@@ -1821,13 +1820,8 @@ of a <var>node</var> into a <var>parent</var> before a
  <li>If <var>child</var> is not null and its <a>parent</a> is not <var>parent</var>, then
  <a>throw</a> a {{NotFoundError}}.
 
- <li>If <var>node</var> is not a
- {{DocumentFragment}}, {{DocumentType}},
- {{Element}}, {{Text}},
- {{ProcessingInstruction}}, or {{Comment}}
- <a>node</a>,
- <a>throw</a> a
- {{HierarchyRequestError}}.
+ <li>If <var>node</var> is not a {{DocumentFragment}}, {{DocumentType}}, {{Element}}, or
+ {{CharacterData}} <a>node</a>, <a>throw</a> a {{HierarchyRequestError}}.
 
  <li>If either <var>node</var> is a {{Text}}
  <a>node</a> and <var>parent</var> is a
@@ -1839,7 +1833,7 @@ of a <var>node</var> into a <var>parent</var> before a
 
  <li>
   If <var>parent</var> is a
-  <a>document</a>, and any of the statements below, switched
+  <a>document</a>, and any of the statements below, depending
   on <var>node</var>, are true, <a>throw</a> a
   {{HierarchyRequestError}}.
 
@@ -2041,13 +2035,8 @@ steps:
  <li>If <var>child</var>'s <a>parent</a> is not <var>parent</var>, then <a>throw</a> a
  {{NotFoundError}}.
 
- <li>If <var>node</var> is not a
- {{DocumentFragment}}, {{DocumentType}},
- {{Element}}, {{Text}},
- {{ProcessingInstruction}}, or {{Comment}}
- <a>node</a>,
- <a>throw</a> a
- {{HierarchyRequestError}}.
+ <li>If <var>node</var> is not a {{DocumentFragment}}, {{DocumentType}}, {{Element}}, or
+ {{CharacterData}} <a>node</a>, <a>throw</a> a {{HierarchyRequestError}}.
 
  <li>If either <var>node</var> is a {{Text}}
  <a>node</a> and <var>parent</var> is a
@@ -2059,7 +2048,7 @@ steps:
 
  <li>
   If <var>parent</var> is a
-  <a>document</a>, and any of the statements below, switched
+  <a>document</a>, and any of the statements below, depending
   on <var>node</var>, are true, <a>throw</a> a
   {{HierarchyRequestError}}.
 
@@ -3460,7 +3449,7 @@ dictionary GetRootNodeOptions {
 
 <p class="note no-backref">{{Node}} is an abstract interface and does not exist as <a>node</a>. It
 is used by all <a>nodes</a> ({{Document}}, {{DocumentType}}, {{DocumentFragment}}, {{Element}},
-{{Text}}, {{ProcessingInstruction}}, and {{Comment}}).
+{{Text}}, {{CDATASection}}, {{ProcessingInstruction}}, and {{Comment}}).
 
 Each <a>node</a> has an associated
 <dfn export for=Node id=concept-node-document>node document</dfn>, set upon creation,
@@ -3524,6 +3513,9 @@ that is a <a>document</a>.
    <dt>{{Text}}
    <dd>"<code>#text</code>".
 
+   <dt>{{CDATASection}}
+   <dd>"<code>#cdata-section</code>".
+
    <dt>{{ProcessingInstruction}}
    <dd>Its <a for=ProcessingInstruction>target</a>.
 
@@ -3542,7 +3534,7 @@ that is a <a>document</a>.
 </dl>
 
 The <dfn attribute for=Node>nodeType</dfn> attribute's getter, when invoked, must return
-the first matching statement, switching on the <a>context object</a>:
+the first matching statement, depending on the <a>context object</a>:
 
 <dl class=switch>
  <dt>{{Element}}
@@ -3603,7 +3595,7 @@ must return the local name that is associated with the node, if it has one,
 and null otherwise.-->
 
 The <dfn attribute for=Node>nodeName</dfn> attribute's getter, when invoked, must return
-the first matching statement, switching on the <a>context object</a>:
+the first matching statement, depending on the <a>context object</a>:
 
 <dl class=switch>
  <dt>{{Element}}
@@ -3619,6 +3611,9 @@ the first matching statement, switching on the <a>context object</a>:
  <dt>{{Text}}
  <dd>"<code>#text</code>".
 
+ <dt>{{CDATASection}}
+ <dd>"<code>#cdata-section</code>".
+
  <dt>{{ProcessingInstruction}}
  <dd>Its <a for=ProcessingInstruction>target</a>.
 
@@ -3750,9 +3745,7 @@ must return the following, depending on the <a>context object</a>:
 
 <dl class=switch>
  <!--AttrExodus <dt>{{Attr}} -->
- <dt>{{Text}}
- <dt>{{ProcessingInstruction}}
- <dt>{{Comment}}
+ <dt>{{CharacterData}}
  <dd>The <a>context object</a>'s
  <a>data</a>.
 
@@ -3766,9 +3759,7 @@ instead, and then do as described below, depending on the <a>context object</a>:
 
 <dl class=switch>
  <!--AttrExodus <dt>{{Attr}} -->
- <dt>{{Text}}
- <dt>{{ProcessingInstruction}}
- <dt>{{Comment}}
+ <dt>{{CharacterData}}
  <dd><a>Replace data</a> with node
  <a>context object</a>, offset 0, count
  {{CharacterData/length}} attribute value, and
@@ -3779,7 +3770,7 @@ instead, and then do as described below, depending on the <a>context object</a>:
 </dl>
 
 <p>The <dfn attribute for=Node><code>textContent</code></dfn> attribute's getter must return the
-following, switching on <a>context object</a>:
+following, depending on the <a>context object</a>:
 
 <dl class=switch>
  <dt>{{DocumentFragment}}
@@ -3791,9 +3782,7 @@ following, switching on <a>context object</a>:
  <a>context object</a>, in
  <a>tree order</a>.
 
- <dt>{{Text}}
- <dt>{{ProcessingInstruction}}
- <dt>{{Comment}}
+ <dt>{{CharacterData}}
  <dd>The <a>context object</a>'s
  <a>data</a>.
 
@@ -3802,7 +3791,7 @@ following, switching on <a>context object</a>:
 </dl>
 
 <p>The {{Node/textContent}} attribute's setter must, if the given value is null, act as if it was
-the empty string instead, and then do as described below, switching on <a>context object</a>:
+the empty string instead, and then do as described below, depending on the <a>context object</a>:
 
 <dl class=switch>
  <dt>{{DocumentFragment}}
@@ -3819,9 +3808,7 @@ the empty string instead, and then do as described below, switching on <a>contex
    <li><p><a>Replace all</a> with <var>node</var> within the <a>context object</a>.
   </ol>
 
- <dt>{{Text}}
- <dt>{{ProcessingInstruction}}
- <dt>{{Comment}}
+ <dt>{{CharacterData}}
  <dd><p><a>Replace data</a> with node <a>context object</a>, offset 0, count
  {{CharacterData/length}} attribute value, and data the given value.
 
@@ -3993,7 +3980,7 @@ dom-Range-extractContents, dom-Range-cloneContents -->
 
  <li>
   <p>Otherwise, let <var>copy</var> be a <a>node</a> that implements the same interfaces as
-  <var>node</var>, and fulfills these additional requirements, switching on
+  <var>node</var>, and fulfills these additional requirements, depending on
   <var>node</var>:
 
   <dl class=switch>