Fix text highlighting in the Font Inspector in the debugger

After PR #5282, the text highlighting in the Font Inspector is very hard to see against a white background. That seems to be an oversight from the mentioned PR, hence this patch fixes that.
Fix a regression preventing page change in the Stepper in the debugger

This is a regression from https://github.com/mozilla/pdf.js/commit/ddd3c8fc2fe7b8715bed6d6f146c206d133b5dd6, which prevents changing pages in the Stepper.

(Apart from fixing the bug, for the sake of consistency, I also removed one instance of `parseInt`.)
Adds readme file for the pdfjs-dist repo.
Merge pull request #5337 from Snuffleupagus/fix-stepper-page-change

Fix a regression preventing page change in the Stepper in the debugger
Merge pull request #5335 from Snuffleupagus/pdfBug-text-highlight

Fix text highlighting in the Font Inspector in the debugger
Merge pull request #5339 from yurydelendik/dist

Adds readme file for the pdfjs-dist repo.