createImageBitmap(): stop clipping sourceRect to source's dimensions

It has been found in #6306 that this was an oversight at the time of its introduction. Current behavior goes against author expectations and no implementer has opposed the change to "no-clip".

Tests: web-platform-tests/wpt#27040.

Closes #6306.

source

@@ -95199,8 +95199,6 @@ dictionary <dfn>ImageBitmapOptions</dfn> {
     <var>sy</var>) point.</p>
    </li>
 
-   <li><p>Clip <var>sourceRectangle</var> to the dimensions of <var>input</var>.</p></li>
-
    <li>
     <p>Let <var>outputWidth</var> be determined as follows:</p>