Remove redundant fetch declarations

[saschanaz]

Fixes #634

[danvk]

What's the process for these changes making their way into the TypeScript repo? I see many changes here but none to lib.dom.d.ts since February.

[sandersn]

1. npm run build in this repo
2. copy files from generated/ into Typescript/src/lib/ -- you should see many updates from this repo there since June at least.
3. On a release, generate a new LKG -- last known good -- that includes lib.dom.d.ts, plus all the typescript binaries, etc.

Step (3) hasn't happened for TS 3.6 yet.

[danvk]

I see, there is TypeScript/lib and TypeScript/src/lib.