Nested Math in Non-Default Text Fix (#1111)

* Fixing nested math in non-default text. Added appropriate screenshot tests.

* Adding appropriate logic for buildMathML and resolving tests.

* Addressing Kevin's comment. Adding tests.

* Adding appropriate screenshots.

* Removing unnecessary data, adding consistent naming convention.

* Cleanup

* Handling possible edge cases.

* Updating per PR comments

test/katex-spec.js

@@ -607,7 +607,7 @@ describe("An implicit group parser", function() {
             expect(tree).toMatchSnapshot();
         });
 
-        it("should work wwith old font functions: \\sqrt[\\tt 3]{x}", () => {
+        it("should work with old font functions: \\sqrt[\\tt 3]{x}", () => {
             const tree = stripPositions(getParsed("\\sqrt[\\tt 3]{x}"));
             expect(tree).toMatchSnapshot();
         });