fix(aria-allowed-role): Add math to allowed roles for img element (#4658)

img element can have 'math' as its role

Closes: #4657

Author: notoriousmango

Diff for: lib/standards/html-elms.js

@@ -360,6 +360,7 @@ const htmlElms = {
           'button',
           'checkbox',
           'link',
+          'math',
           'menuitem',
           'menuitemcheckbox',
           'menuitemradio',

Diff for: test/integration/rules/aria-allowed-role/aria-allowed-role.html

@@ -258,6 +258,7 @@ <h1 id="pass-h1-valid-role" role="none"></h1>
   id="pass-img-valid-role-meter"
 />
 <img role="doc-cover" aria-label="foo" id="pass-img-valid-role-aria-label" />
+<img role="math" aria-label="test" id="pass-img-valid-role-math" />
 <img role="menuitem" title="bar" id="pass-img-valid-role-title" />
 <div id="image-baz">hazaar</div>
 <img

Diff for: test/integration/rules/aria-allowed-role/aria-allowed-role.json

@@ -83,6 +83,7 @@
     ["#pass-img-valid-role-title"],
     ["#pass-img-valid-role-aria-labelledby"],
     ["#pass-img-valid-role-radio"],
+    ["#pass-img-valid-role-math"],
     ["#pass-img-valid-role-meter"],
     ["#pass-imgmap-1"],
     ["#pass-imgmap-2"],