Add a test that access a property name in its unicode escaped form.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@30 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

test/mjsunit/bugs/bug-1346700.js

+var o = {"\u59cb\u53d1\u7ad9": 1};
+assertEquals(1, o.\u59cb\u53d1\u7ad9);