docs: add changelog for 5.1.3

Author: mhevery

CHANGELOG.md

@@ -1,3 +1,17 @@
+<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="5.1.2"></a>
 ## [5.1.2](https://github.com/angular/angular/compare/5.1.1...5.1.2) (2017-12-20)