Handle JSDoc @param with hyphen

**TypeScript Version:** 2.7.0-dev.20171214 **Code** ```ts /** * @param x - Bla */ function foo(x) { } ``` Hover over `x` **Expected behavior:** Hyphen is ignored in any documentation returned. See JSDoc @param spec: http://usejsdoc.org/tags-param.html **Actual behavior:** Hyphen is returned as part of documentation: ``` [Trace - 2:58:07 PM] Response received: quickinfo (144). Request took 3 ms. Success: true Result: { "kind": "parameter", "kindModifiers": "", "start": { "line": 4, "offset": 14 }, "end": { "line": 4, "offset": 15 }, "displayString": "(parameter) x: any", "documentation": "- Bla", "tags": [] } ```