Core: Simplify code post browser support reduction

Core: Simplify code post browser support reduction

Summary of the changes:
* Tests: Remove legacy jQuery.cache & oldIE leftovers
* Tests: Reformat JavaScript in delegatetest.html
* Docs: "jQuery Foundation Projects" -> "jQuery Projects"
* Tests: Drop an unused localfile.html file (modern browsers don't support
  the `file:` protocol this way, there's no point in keeping the file around)
* Effects: Remove a redundant `!fn` check (`fn || !fn && easing` is equivalent
  to `fn || easing`; simplify the code)
* CSS: Explain the fallback to direct object access in curCSS better
* Tests: Deduplicate `jQuery.parseHTML` test titles
* Dimensions: Add a test for fractional values
* Tests: Fix a buggy WebKit regex

Closes gh-5296

(cherry picked from commit 93ca49e6d1ac23fee33b3bc3b7f4d93dd1a25cb7)