message: docs: add changelog for 5.1.3
diff: +<a name="5.1.3"></a>
  +## [5.1.3](https://github.com/angular/angular/compare/5.1.2...5.1.3) (2018-01-03)
  +
  +
  +### Bug Fixes
  +
  +* **animations:** avoid infinite loop with multiple blocked sub triggers ([#21119](https://github.com/angular/angular/issues/21119)) ([3e34fa8](https://github.com/angular/angular/commit/3e34fa8))
  +* **animations:** renaming issue with DOMAnimation. ([#21125](https://github.com/angular/angular/issues/21125)) ([d1f4500](https://github.com/angular/angular/commit/d1f4500))
  +* **common:** handle JS floating point errors in percent pipe ([#20329](https://github.com/angular/angular/issues/20329)) ([fa0e8ef](https://github.com/angular/angular/commit/fa0e8ef)), closes [#20136](https://github.com/angular/angular/issues/20136)
  +* **language-service:** ignore null metadatas ([#20557](https://github.com/angular/angular/issues/20557)) ([48a1f32](https://github.com/angular/angular/commit/48a1f32)), closes [#20260](https://github.com/angular/angular/issues/20260)
  +* **router:** fix wildcard route with lazy loaded module (again) ([#18139](https://github.com/angular/angular/issues/18139)) ([8c99175](https://github.com/angular/angular/commit/8c99175)), closes [#13848](https://github.com/angular/angular/issues/13848)
  +
  +
  <a name="5.2.0-beta.1"></a>
  # [5.2.0-beta.1](https://github.com/angular/angular/compare/5.2.0-beta.0...5.2.0-beta.1) (2017-12-20)
  