Post revisions: Make diff content visible on MS Edge Win 10

[frontdevde]

This PR

• fixes an issue that caused Diff content to not be visible on MS Edge Win 10

The Issue was caused by using window.scrollTo on an element. Webkit based browsers and Firefox auto-correct the behavior and allow the use of window.scrollTo on an element as well. IE/Edge, on the other hand, is less forgiving. So in Edge, this caused an error that stopped further execution and thus prevented the revision content from being displayed. The straightforward solution to the problem is to use Element.scrollTop instead.

How to test

• Open the latest version of the Edge browser on Windows 10
  (Tip: If you don't have a local version you can use our browserstack.com account.)
• Navigate to or create a post with revisions
• Click on the History button to trigger the Post Revisions modal
• The revisions should load including their content
• It should look like the After state, not like the before state
• The revision content window should scroll to the first revised word

Next:

• Open the latest version of Chrome on Mac OS X or Windows
• Proceed in this browser with the same process as described above
• Open wpcalypso.wordpress.com in a second tab
• Repeat the same process in the second tab as described above
• The behavior in tab 1 and tab 2 should be identical

Before

After

[matticbot]

Test live: https://calypso.live/?branch=fix/post-revisions/ms-edge-scrollto-issue

[jblz]

Working well on latest Chrome Mac & Edge Win 10 (browserstack)