Relax feature-detection for <menclose>

Discussion is still open: w3c/mathml#105
so let's only check some minimal <mrow> support.

Igalia does not plan to implement this element in Chromium for now so
making detection too strict is causing test failures.

mathml/support/feature-detection.js

@@ -24,35 +24,11 @@ var MathMLFeatureDetection = {
  },
 
  "has_menclose": function() {
- if (!this.hasOwnProperty("_has_menclose")) {
- document.body.insertAdjacentHTML("beforeend", "<math>\
-<mrow style='font-size: 20px !important'>\
- <mrow>\
- <mrow>\
- <mrow>\
- <mtext>A</mtext>\
- </mrow>\
- </mrow>\
- </mrow>\
-</mrow>\
-<menclose notation='box' style='font-size: 20px !important'>\
- <menclose notation='box'>\
- <menclose notation='box'>\
- <menclose notation='box'>\
- <mtext>A</mtext>\
- </menclose>\
- </menclose>\
- </menclose>\
-</menclose>\
-</math>");
- var math = document.body.lastElementChild;
- // The boxes will make menclose wider than mrow, if the former is supported.
- this._has_menclose =
- math.lastElementChild.getBoundingClientRect().width -
- math.firstElementChild.getBoundingClientRect().width > 5;
- document.body.removeChild(math);
- }
- return this._has_menclose;
+ // Just check whether <mrow> is supported because discussion on this is
+ // still open ( https://github.com/mathml-refresh/mathml/issues/105 )
+ // and it would have to behave at least like an mrow, even if it becomes
+ // an unknown element at the end.
+ return this.has_mrow();
  },
 
  "has_merror": function() {