Remove overridden getUserRoles method

In c7b550e There was a new `getUserRoles` method added, but the old
version was left in place too, overriding the new method. Oops! Let's
clear that old way out to make room for the new.

Author: noahsilas

src/Auth.js

@@ -169,6 +169,7 @@ var getAuthForLegacySessionToken = function({
   });
 };
 
+// Returns a promise that resolves to an array of role names
 Auth.prototype.getUserRoles = function () {
   if (this.isMaster || !this.user) {
     return Promise.resolve([]);
@@ -293,21 +294,6 @@ Auth.prototype._generateRoleGraphPipeline = function () {
   ];
 };
 
-// Returns a promise that resolves to an array of role names
-Auth.prototype.getUserRoles = function() {
-  if (this.isMaster || !this.user) {
-    return Promise.resolve([]);
-  }
-  if (this.fetchedRoles) {
-    return Promise.resolve(this.userRoles);
-  }
-  if (this.rolePromise) {
-    return this.rolePromise;
-  }
-  this.rolePromise = this._loadRoles();
-  return this.rolePromise;
-};
-
 Auth.prototype.getRolesForUser = async function() {
   //Stack all Parse.Role
   const results = [];