Editorial: use "identity matrix" consistently

Previously we used a mix of "identity matrix" and "identity transform".

Closes whatwg#3426.

Author: TimvdLippe

source

@@ -61908,7 +61908,7 @@ try {
   <p>Objects that implement the <code>CanvasTransform</code> interface have a <dfn>current
   transformation matrix</dfn>, as well as methods (described in this section) to manipulate it. When
   an object implementing the <code>CanvasTransform</code> interface is created, its transformation
-  matrix must be initialized to the identity transform.</p>
+  matrix must be initialized to the identity matrix.</p>
 
   <p>The <span>current transformation matrix</span> is applied to coordinates when creating the
   <span>current default path</span>, and when painting text, shapes, and <code>Path2D</code>
@@ -61995,7 +61995,7 @@ try {
 
    <dd>
 
-    <p>Changes the <span>current transformation matrix</span> to the identity transform.</p>
+    <p>Changes the <span>current transformation matrix</span> to the identity matrix.</p>
 
    </dd>
 
@@ -62584,7 +62584,7 @@ try {
   not affect the pattern(s) rendered by the <code>CanvasPattern</code> object.</p>
 
   <p>Patterns have a transformation matrix, which controls how the pattern is used when it is
-  painted. Initially, a pattern's transformation matrix must be the identity transform.</p>
+  painted. Initially, a pattern's transformation matrix must be the identity matrix.</p>
 
   <p>The <dfn><code
   data-x="dom-canvaspattern-setTransform">setTransform(<var>transform</var>)</code></dfn> method,