Add test suite for jquery.byteLimit:

Add test suite for jquery.byteLimit:
- Tests to verify that the byteLength does not exceed the byteLimit when inserting more characters
- Tests to verify that it doesn't prevent too early (ie. if limit is 10 and we insert 20 characters, there should be 10 characters in the input field).

This test suite has exposed that the latter is currently broken. jquery.byteLimit is preventing characters to be added as soon as byteLength(currentValue) + 3 is more than the given limit.

(Follows-up r86698, r91148)