Last minute bug fix in StyleManager Changes

Odd this wasn't caught in our initial specs. But this issue only effects specs, as the actual production code is able to assign the callback with a function reference rather than a string which is then used to assign the callback itself.

src/style-manager.js

@@ -237,7 +237,7 @@ module.exports = class StyleManager {
     // Allows us to utilize a direct callback, or if calling from outside
     // StyleManager we can define a string that works
     if (upgradeName === "math") {
-      cb = upgradeDeprecatedMathUsageForStyleSheet;
+      cb = transformDeprecatedMathUsage;
     } else if (upgradeName === "selector") {
       cb = transformDeprecatedShadowDOMSelectors;
     } else if (typeof upgradeName === "function") {