chore(package): update @angular/platform-browser to version 5.2.1

Closes #54

Author: greenkeeper[bot]

package.json

@@ -77,7 +77,7 @@
     "@angular/compiler-cli": "^4.1.3",
     "@angular/core": "^4.1.3",
     "@angular/forms": "^4.1.3",
-    "@angular/platform-browser": "^4.1.3",
+    "@angular/platform-browser": "^5.2.1",
     "@angular/platform-browser-dynamic": "^4.1.3",
     "@types/jasmine": "2.5.53",
     "@types/node": "^8.0.0",