Add an unit test checking the query of child
Add an unit test checking the query of child

This test case is intended to highlight two unwanted behaviors:
- The first one is related to issue #742. While using css-select v1.0.0, the child selector '>' would also include indirect descendants and this test case would return '3'.
- The second issue (discussed here: https://github.com/cheeriojs/cheerio/issues/780#issuecomment-166696996 ) comes while using css-select v1.2.0. In such a case, the context of the '>' selector is the first 'bar' and not 'foo' as intended, which causes a resulting length of '2'.

cheeriojs/cheerio,cheeriojs/cheerio