Improve stopping at errors. (#2278)

In some cases the debugger catches (reports) the same
exception multiple times. This is confusing since these
not new errors. This patch fixes this behaviour.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

tests/debugger/do_throw_adv.cmd

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