chore(deps): update dependency typescript to v2.8.4 (#63)

Author: renovate[bot]

package.json

@@ -60,7 +60,7 @@
     "rollup-plugin-terser": "1.0.1",
     "scroll-into-view-if-needed": "2.2.4",
     "semantic-release": "15.5.0",
-    "typescript": "2.8.3"
+    "typescript": "2.8.4"
   },
   "keywords": [
     "behavior-smooth",

yarn.lock

@@ -4996,9 +4996,9 @@ typedarray@^0.0.6:
   version "0.0.6"
   resolved "https://registry.yarnpkg.com/typedarray/-/typedarray-0.0.6.tgz#867ac74e3864187b1d3d47d996a78ec5c8830777"
 
-typescript@2.8.3:
-  version "2.8.3"
-  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.8.3.tgz#5d817f9b6f31bb871835f4edf0089f21abe6c170"
+typescript@2.8.4:
+  version "2.8.4"
+  resolved "https://registry.yarnpkg.com/typescript/-/typescript-2.8.4.tgz#0b1db68e6bdfb0b767fa2ab642136a35b059b199"
 
 ua-parser-js@^0.7.9:
   version "0.7.17"