feat: support MathML \big, \bigg, \Big, and \Bigg (#2332)

* Support MathML \big, \bigg, etc

* Add stretchy attribute

* Update mathml-spec.js.snap

Co-authored-by: ylemkimon <y@ylem.kim>

src/delimiter.js

@@ -782,6 +782,7 @@ const makeLeftRightDelim = function(
 export default {
     sqrtImage: makeSqrtImage,
     sizedDelim: makeSizedDelim,
+    sizeToMaxHeight: sizeToMaxHeight,
     customSizedDelim: makeCustomSizedDelim,
     leftRightDelim: makeLeftRightDelim,
 };

src/functions/delimsizing.js

@@ -124,6 +124,10 @@ defineFunction({
             node.setAttribute("fence", "false");
         }
 
+        node.setAttribute("stretchy", "true");
+        node.setAttribute("minsize", delimiter.sizeToMaxHeight[group.size] + "em");
+        node.setAttribute("maxsize", delimiter.sizeToMaxHeight[group.size] + "em");
+
         return node;
     },
 });