This API was introduced only in a beta release, and is being removed because we found it to be incorrect prior to launch. For more information about why this is being removed, see https://github.com/angular/angular/pull/15050.
TypeScript compiler will now build to ES2015 code and modules. Babili is used to minify ES2015
code, providing an initial optimization that we couldn't previously get just from Uglify. Uses
Babel to convert ES2015 to UMD/ES5 code, and Uglify to minimize the output.