Don't hardcode number of result providers

[nicksnyder]

Minor refactor. Does not change any logic.

[chrmarti]

Thanks for your contribution @nicksnyder. A few thoughts:

Instead of searching and casting for the FileQuickOpenModel, could we just .then on the promise we know returns that model: https://github.com/Microsoft/vscode/blame/master/src/vs/workbench/parts/search/browser/openAnythingHandler.ts#L164

Also: [].concat(...results.map(r => r.entries)) would be shorter and maybe slightly more efficient than the reduce approach.

[nicksnyder]

@chrmarti Thanks for the suggestions! I updated the PR.

[chrmarti]

Thanks @nicksnyder !