Update TypeScript devDependency.

Author: DanielRosenwasser

package.json

@@ -118,7 +118,7 @@
     "selenium-server": "^2.53.1",
     "serialize-javascript": "^1.3.0",
     "shelljs": "^0.7.8",
-    "typescript": "2.5.0-dev.20170615",
+    "typescript": "^2.4.2",
     "uglify-js": "^3.0.15",
     "webpack": "^2.6.1",
     "weex-js-runtime": "^0.20.5",