Update link-to-wiki generator
Remove TextDecoder feature tests

TextDecoder is not required by PDF.js any more, and the wiki entry has been deleted as well:
https://github.com/mozilla/pdf.js/wiki/Required-Browser-Features/_compare/13ddaa98459236169c1d7969f00fa5610bf7e10f...09aac34e58549698930735bdd10685b9ee54a9ac
Merge pull request #5247 from Rob--W/wiki-test-link-gen

Fix links to wiki subsections and remove TextDecoder feature tests