Editorial: add a definition for canvas width/height numeric values

Previously, this concept was informally defined and referred to. Now it
is properly defined with a <dfn>, and cross-referenced.

Fixes whatwg#2066.

Author: Donovan Glover

source

@@ -59248,13 +59248,14 @@ callback <dfn>BlobCallback</dfn> = void (<span>Blob</span>? blob);</pre>
   <hr>
 
   <p>The <code>canvas</code> element has two attributes to control the size of the element's bitmap:
-  <dfn><code data-x="attr-canvas-width">width</code></dfn> and <dfn><code data-x="attr-canvas-height">height</code></dfn>. These attributes, when specified, must have
+  <dfn><code data-x="attr-canvas-width">width</code></dfn> and <dfn><code
+  data-x="attr-canvas-height">height</code></dfn>. These attributes, when specified, must have
   values that are <span data-x="valid non-negative integer">valid non-negative integers</span>. <span
-  w-nodev>The <span>rules for parsing non-negative integers</span> must be used to obtain their
-  numeric values. If an attribute is missing, or if parsing its value returns an error, then the
-  default value must be used instead.</span> The <code data-x="attr-canvas-width">width</code>
-  attribute defaults to 300, and the <code data-x="attr-canvas-height">height</code> attribute
-  defaults to 150.</p>
+  w-nodev>The <span>rules for parsing non-negative integers</span> must be used to <dfn
+  data-x="obtain-numeric-values">obtain their numeric values</dfn>. If an attribute is missing,
+  or if parsing its value returns an error, then the default value must be used instead.</span>
+  The <code data-x="attr-canvas-width">width</code> attribute defaults to 300, and the
+  <code data-x="attr-canvas-height">height</code> attribute defaults to 150.</p>
 
   <p>When setting the value of the <code data-x="attr-canvas-width">width</code> or <code
   data-x="attr-canvas-height">height</code> attribute, if the <span
@@ -59298,8 +59299,9 @@ callback <dfn>BlobCallback</dfn> = void (<span>Blob</span>? blob);</pre>
   <p>When its <span data-x="concept-canvas-context-mode">canvas context mode</span> is <span
   data-x="concept-canvas-none">none</span>, a <code>canvas</code> element has no rendering context,
   and its bitmap must be <span>transparent black</span> with an <span>intrinsic width</span> equal
-  to the numeric value of the element's <code data-x="attr-canvas-width">width</code> attribute and
-  an <span>intrinsic height</span> equal to the numeric value of the element's <code
+  to <span data-x="obtain-numeric-values">the numeric value</span> of the element's <code
+  data-x="attr-canvas-width">width</code> attribute and an <span>intrinsic height</span> equal to
+  <span data-x="obtain-numeric-values">the numeric value</span> of the element's <code
   data-x="attr-canvas-height">height</code> attribute, those values being interpreted in <span
   data-x="'px'">CSS pixels</span>, and being updated as the attributes are set, changed, or
   removed.</p>
@@ -59335,8 +59337,9 @@ callback <dfn>BlobCallback</dfn> = void (<span>Blob</span>? blob);</pre>
       <p><span data-x="concept-canvas-2d">2d</span></p>
      <td>
       <p>Follow the steps to <span data-x="concept-canvas-set-bitmap-dimensions">set bitmap
-      dimensions</span> to the numeric values of the <code data-x="attr-canvas-width">width</code>
-      and <code data-x="attr-canvas-height">height</code> content attributes.</p>
+      dimensions</span> to <span data-x="obtain-numeric-values">the numeric values</span>
+      of the <code data-x="attr-canvas-width">width</code> and <code
+      data-x="attr-canvas-height">height</code> content attributes.</p>
 
     <tr>
      <th>
@@ -60029,9 +60032,10 @@ interface <dfn>Path2D</dfn> {
    <li><p>Set <var>context</var>'s <span>output bitmap</span> to the same bitmap as
    <var>target</var>'s bitmap (so that they are shared).</p></li>
 
-   <li><p><span data-x="concept-canvas-set-bitmap-dimensions">Set bitmap dimensions</span> to the
-   numeric values of <var>target</var>'s <code data-x="attr-canvas-width">width</code> and
-   <code data-x="attr-canvas-height">height</code> content attributes.</p></li>
+   <li><p><span data-x="concept-canvas-set-bitmap-dimensions">Set bitmap dimensions</span> to
+   <span data-x="obtain-numeric-values">the numeric values</span> of <var>target</var>'s <code
+   data-x="attr-canvas-width">width</code> and <code data-x="attr-canvas-height">height</code>
+   content attributes.</p></li>
 
    <li>
     <p>Process each of the members of <var>settings</var> as follows:</p>
@@ -60061,13 +60065,15 @@ interface <dfn>Path2D</dfn> {
    <li><p>Let <var>canvas</var> be the <code>canvas</code> element to which the rendering
    context's <code data-x="dom-context-2d-canvas">canvas</code> attribute was initialized.</p></li>
 
-   <li><p>If the numeric value of <var>canvas</var>'s <code data-x="attr-canvas-width">width</code>
-   content attribute differs from <var>width</var>, then set <var>canvas</var>'s <code
+   <li><p>If <span data-x="obtain-numeric-values">the numeric value</span> of
+   <var>canvas</var>'s <code data-x="attr-canvas-width">width</code> content
+   attribute differs from <var>width</var>, then set <var>canvas</var>'s <code
    data-x="attr-canvas-width">width</code> content attribute to the shortest possible string
    representing <var>width</var> as a <span>valid non-negative integer</span>.</p></li>
 
-   <li><p>If the numeric value of <var>canvas</var>'s <code data-x="attr-canvas-height">height</code>
-   content attribute differs from <var>height</var>, then set <var>canvas</var>'s <code
+   <li><p>If <span data-x="obtain-numeric-values">the numeric value</span> of
+   <var>canvas</var>'s <code data-x="attr-canvas-height">height</code> content
+   attribute differs from <var>height</var>, then set <var>canvas</var>'s <code
    data-x="attr-canvas-height">height</code> content attribute to the shortest possible string
    representing <var>height</var> as a <span>valid non-negative integer</span>.</p></li>
 
@@ -64716,11 +64722,12 @@ dictionary <dfn>ImageBitmapRenderingContextSettings</dfn> {
 
      <li><p>Set <var>context</var>'s <span
      data-x="concept-ImageBitmapRenderingContext-output-bitmap">output bitmap</span> to be
-     <span>transparent black</span> with an <span>intrinsic width</span> equal to the numeric value
-     of <var>canvas</var>'s <code data-x="attr-canvas-width">width</code> attribute and an
-     <span>intrinsic height</span> equal to the numeric value of <var>canvas</var>'s <code
-     data-x="attr-canvas-height">height</code> attribute, those values being interpreted in <span
-     data-x="'px'">CSS pixels</span>.</p></li>
+     <span>transparent black</span> with an <span>intrinsic width</span> equal to <span
+     data-x="obtain-numeric-values">the numeric value</span> of <var>canvas</var>'s <code
+     data-x="attr-canvas-width">width</code> attribute and an <span>intrinsic height</span> equal
+     to <span data-x="obtain-numeric-values">the numeric value</span> of <var>canvas</var>'s
+     <code data-x="attr-canvas-height">height</code> attribute, those values being interpreted
+     in <span data-x="'px'">CSS pixels</span>.</p></li>
 
      <li><p>Set the <span
      data-x="concept-ImageBitmapRenderingContext-output-bitmap">output bitmap</span>'s <span