tsserver.js hangs until typingsinstaller.js process is killed

[minestarks]

TypeScript Version: Tried and reproduced on 2.2, 2.3, and current

Visual Studio Version: Tried and reproduced on 15.2 and 15.3. Bug won't repro with the below steps on 15.4 because of a different fix in multi-project scenario.

1. Open a Visual Studio solution with a ton of (100?) C# projects.

   • This step is necessary because it causes tsserver to create a ton of empty projects with just lib.d.ts. This is the part that was mitigated in 15.4.

2. Open one JavaScript file.

3. Observe VS and observe node.exe activity in Task Manager.

Outcome:

• After a little bit of doing work, the two Node processes running tsserver and typingsinstaller both hang (no CPU activity).
• As a result of the hang it looks like the JS/TS language service quit working in VS.
• tsserver appears to be blocked waiting on typingsinstaller, since explicitly killing the typingsinstaller Node process will let tsserver make progress again. The language service in VS will now start working.