Fix nontermination issue in the full-fidelity parser
Summary:
Colon after a possible binary expression was causing an infinite loop because no progress was being made. Removing this allows the program to terminate with errors instead on the following expression:
$func = (): int ==> 1;
Talked with ericlippert, and decided that colons don't need to belong in this category and that we will explicitly handle ternary operations instead.
Differential Revision:
D3429102
fbshipit-source-id:
55f7e09fb348ba5ddf0968795db39593a61d5cfe