Whitelist closure related cases to address the remaining no-shadow linting errors

Given the way that "classes" were previously implemented in PDF.js, using regular functions and closures, there's a fair number of false positives when the `no-shadow` ESLint rule was enabled.

Note that while *some* of these `eslint-disable` statements can be removed if/when the relevant code is converted to proper `class`es, we'll probably never be able to get rid of all of them given our naming/coding conventions (however I don't really see this being a problem).

src/core/ps_parser.js

@@ -113,6 +113,7 @@ const PostScriptTokenTypes = {
 const PostScriptToken = (function PostScriptTokenClosure() {
   const opCache = Object.create(null);
 
+  // eslint-disable-next-line no-shadow
   class PostScriptToken {
     constructor(type, value) {
       this.type = type;