Support multi-line jsdoc annotations

- VSCode Version: 1.12.2
- OS Version: macOS 10.12.5

Steps to Reproduce:

1. Open a javascript file with multi-line type annotations. For example:
https://github.com/google/closure-library/blob/master/closure/goog/dom/animationframe/animationframe.js#L61

Expected result:
VSCode highlights the jsdoc.

Actual Result:
VSCode highlights the jsdoc in red like there's an error.
