quick outline (symbol list) doesn't contain exported types

[dbaeumer]

From @jrieken on January 28, 2016 8:53

• open vscode.d.ts
• open quick outline and type MarkedString
• it doesn't show-up, tho it is defined on line 1369

Copied from original issue: microsoft/vscode#2482

[dbaeumer]

These are already missing in the corresponding response from the tsserver. Moving to TypeScript