message: docs: add changelog for the v4.4.7 release
diff: +<a name="4.4.7"></a>
  +## [4.4.7](https://github.com/angular/angular/compare/4.4.6...4.4.7) (2018-04-16)
  +
  +
  +### Bug Fixes
  +
  +* **core:** use appropriate inert document strategy for Firefox & Safari ([#22077](https://github.com/angular/angular/issues/22077)) ([2c5cf19](https://github.com/angular/angular/commit/2c5cf19))
  +
  +
  +
  <a name="6.0.0-rc.5"></a>
  ## [6.0.0-rc.5](https://github.com/angular/angular/compare/6.0.0-rc.4...6.0.0-rc.5) (2018-04-14)
  