Handle JSDoc @param with hyphen

TypeScript Version: 2.7.0-dev.20171214

Code

/**
 * @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": []
}

从 issue 中显示的 quickinfo hover 响应所使用的 TypeScript JSDoc @param 处理开始。重现该示例，跟踪文档字符串的形成位置，并验证返回的文档省略了分隔连字符，同时保留了描述。