Code duplication

[shvabuk]

TypeScript Version: 2.6.2
Code duplication in files:

Duplication in file: lib.d.ts on lines: 4862 & 18427
Duplication in file: lib.dom.d.ts on lines: 776 & 14341
Duplication in file: lib.es2016.full.d.ts on lines: 779 & 14344
Duplication in file: lib.es2017.full.d.ts on lines: 783 & 14348
Duplication in file: lib.es6.d.ts on lines: 6549 & 20114
Duplication in file: lib.esnext.full.d.ts on lines: 780 & 14345
Duplication in file: lib.webworker.d.ts on lines: 1882 & 1900

Actual:
https://github.com/Microsoft/TypeScript/blob/master/lib/lib.webworker.d.ts#L1882
https://github.com/Microsoft/TypeScript/blob/master/lib/lib.webworker.d.ts#L1900

According to microsoft/TypeScript#20473

searchDuplicates script: https://gist.github.com/shvabuk/ad6b9974794dc7595c5832722df443fa

[mhegazy]

These files are not meant to be used together. currently the compiler if no --lib is specified, it needs a single library file to include.

microsoft/TypeScript#15780 will allow us to split these files and add references to them instead of having to duplicate the code.