Add some comments to the MathMLElement webidl

Author: Philipp-M

crates/web-sys/webidls/enabled/MathMLElement.webidl

@@ -12,8 +12,11 @@
 
 [Exposed=Window]
 interface MathMLElement : Element { };
+// https://www.w3.org/TR/mathml-core/#dom-and-javascript
 MathMLElement includes GlobalEventHandlers;
 MathMLElement includes HTMLOrSVGElement;
+// https://drafts.csswg.org/cssom/#the-elementcssinlinestyle-mixin
 MathMLElement includes ElementCSSInlineStyle;
+// https://w3c.github.io/touch-events/#extensions-to-the-globaleventhandlers-mixin
 MathMLElement includes TouchEventHandlers;
 MathMLElement includes OnErrorEventHandlerForNodes;