* Add test case
* Fix infer from usage property assignment
Property assignment and shorthand property assignment were incorrectly
treated differently; both have ObjectLiteralExpression as a parent, but
the code previously assumed that property assignments had
ObjectLiteralExpression as parent.parent.
Also make fourslash directives case insensitive and less whitespace
sensitive.
* Add "incorrect 3-slash" error to fourslash parsing.
