Support @class in JSDoc

[mjbvz]

From microsoft/vscode#15168

For the following JavaScript code:

/**
 * @class
 * 
 * @param {number} x
 */
function Foo(x) {
    this.x = x
}

/**
 * @param {Foo} foo
 */
const request = function(foo) {

}

The @class jsdoc annotation for Foo does not seem to be recognized, so the type of foo in request is any:

Changing the code to use class fixes the issue (you don't actually need the @class in this case):

[rubiesonthesky]

Still can be repro'ed in playground. In VS Code, hover shows correct type.

// @noImplicitAny: false
// @noImplicitThis: false
/**
 * @class
 * 
 * @param {number} x
 */
function Foo(x) {
    this.x = x
}

/**
 * @param {Foo} foo
 */
const request = function(foo) {
//                       ^?
}

Workbench Repro