Refactor

* Move the isCompliant() check into getNavTiming(), so it doesn't have to be
  repeated. (And make getNavTiming() return an empty object if browser is not
  compliant.)
* Make getPaintTiming() return duration (i.e., time relative to some reference
  point) rather than absolute values, making it consistent with the way we log
  other Navigation Timing data. (This is the same approach taken by
  <https://github.com/addyosmani/timing.js/>).
* Don't log Chrome's firstPaintAfterLoadTime, which has no analog in other
  browsers, and is therefore less useful than firstPaintTime.
* getMediaWikiTiming() was badly named, because its purpose was primarily to
  get information about the page context (rather than timing data). Move its
  code to emitNavigationTiming() instead.
* Feature-test for chrome.loadTiming rather than try / catch.
* Stop logging the runtime for SaveTiming, now that Zend is no longer serving
  web requests.
* Remove ext.navigationTiming.HHVM.js; no longer needed.
* Schema changes: SCID 10785299, SCID 10785754
* Bump version to 1.0.

Change-Id: I6a2a94c27df264beb00dbf5384b782c3affd1e27
Merge "Refactor"