* Remove now unnecessary portions of build.
* Add a compilePackageES5 method to build ES5 from sources
* Rework all package.json and rollup config files to new format
* Remove "extends" from tsconfig-build.json files and fixup compilation roots
PR Close#18541
The latest rxjs release works with closure compiler out of the box.
We no longer need to compile our own.
Also put closure options into a file rather than using a shell script.
Victor Berchet
Igor Minar
Torgeir Helgevold
Jason Aden
Alex Eagle