Introduce three new extended attribute grammars

These new grammars will be used by the HTML spec for attribute reflection extended attributes.

Author: lukewarlow

index.bs

@@ -6802,7 +6802,7 @@ grammar symbol matches nearly any sequence of tokens, however the
 defined in this document only accept a more restricted syntax.
 Any extended attribute encountered in an
 [=IDL fragment=] is
-matched against the following five grammar symbols to determine
+matched against the following eight grammar symbols to determine
 which form (or forms) it is in:
 
 <table class="vert data">
@@ -6855,6 +6855,39 @@ which form (or forms) it is in:
             <code>[PutForwards=name]</code>
         </td>
     </tr>
+    <tr>
+        <td>
+            <emu-nt><a href="#prod-ExtendedAttributeString">ExtendedAttributeString</a></emu-nt>
+        </td>
+        <td>
+            <dfn id="dfn-xattr-string" for="extended attribute" export>takes a string</dfn>
+        </td>
+        <td>
+            <code>[Reflect="popover"]</code>
+        </td>
+    </tr>
+    <tr>
+        <td>
+            <emu-nt><a href="#prod-ExtendedAttributeNumber">ExtendedAttributeNumber</a></emu-nt>
+        </td>
+        <td>
+            <dfn id="dfn-xattr-number" for="extended attribute" export>takes an integer or decimal</dfn>
+        </td>
+        <td>
+            <code>[ReflectDefault=2.0]</code>
+        </td>
+    </tr>
+    <tr>
+        <td>
+            <emu-nt><a href="#prod-ExtendedAttributeIntegerList">ExtendedAttributeIntegerList</a></emu-nt>
+        </td>
+        <td>
+            <dfn id="dfn-xattr-integer-list" for="extended attribute" export>takes an integer list</dfn>
+        </td>
+        <td>
+            <code>[ReflectRange=(2, 600)]</code>
+        </td>
+    </tr>
     <tr>
         <td>
             <emu-nt><a href="#prod-ExtendedAttributeIdentList">ExtendedAttributeIdentList</a></emu-nt>
@@ -6988,6 +7021,17 @@ five forms are allowed.
         ε
 </pre>
 
+<pre class="grammar" id="prod-IntegerList">
+    IntegerList :
+        integer Integers
+</pre>
+
+<pre class="grammar" id="prod-Integers">
+    Integers :
+        "," integer Integers
+        ε
+</pre>
+
 <pre class="grammar" id="prod-ExtendedAttributeNoArgs">
     ExtendedAttributeNoArgs :
         identifier
@@ -7003,6 +7047,17 @@ five forms are allowed.
         identifier "=" identifier
 </pre>
 
+<pre class="grammar" id="prod-ExtendedAttributeString">
+    ExtendedAttributeString :
+        identifier "=" string
+</pre>
+
+<pre class="grammar" id="prod-ExtendedAttributeNumber">
+    ExtendedAttributeNumber :
+        identifier "=" integer
+        identifier "=" decimal
+</pre>
+
 <pre class="grammar" id="prod-ExtendedAttributeWildcard">
     ExtendedAttributeWildcard :
         identifier "=" "*"
@@ -7013,6 +7068,11 @@ five forms are allowed.
         identifier "=" "(" IdentifierList ")"
 </pre>
 
+<pre class="grammar" id="prod-ExtendedAttributeIntegerList">
+    ExtendedAttributeIntegerList :
+        identifier "=" "(" IntegerList ")"
+</pre>
+
 <pre class="grammar" id="prod-ExtendedAttributeNamedArgList">
     ExtendedAttributeNamedArgList :
         identifier "=" identifier "(" ArgumentList ")"