refactor(angular.js): improve trim performance
refactor(angular.js): improve trim performance

According to Flagrant Badassery's blog
http://blog.stevenlevithan.com/archives/faster-trim-javascript
and this comparison http://jsperf.com/trim-function, this trim method is faster.

Closes #4406

ammula88/angular.js,ammula88/angular.js,ammula88/angular.js,ammula88/angular.js,ammula88/angular.js