Remove unnecessary and unimplemented canvas tainting when painting text

As discussed in whatwg#1540, this check does not give any additional
protections over those already provided by CORS, which these days fonts
are subject to.

Fixes whatwg#1540. Helps with whatwg#1431.

source

@@ -62681,18 +62681,6 @@ try {
 
  </li>
 
-<!--ADD-TOPIC:Security-->
- <li><p>If the <span>text preparation algorithm</span> used a font that has an <span>origin</span>
- that is not the <span data-x="same origin">same</span> as the <span>origin</span> specified by
- the <span>entry settings object</span> (even if "using a font" means just checking if that font
- has a particular glyph in it before falling back to another font), then set the
- <code>CanvasRenderingContext2D</code>'s <span
- data-x="concept-canvas-origin-clean">origin-clean</span> flag to false.</p></li>
- <!-- because fonts could be considered sensitive material, I guess; and because that
- sensitivity could extend to whether or not a particular glyph is in the font in the first place.
- -->
-<!--REMOVE-TOPIC:Security-->
-
  </ol>
 
 <!--v6DVT - this is commented out until CSS can get its act together