Fix tools/run-tests.py --test262-es2015 (#3803)
Fix tools/run-tests.py --test262-es2015 (#3803)

The output of the test262 runner changed between ES5.1 and ES6,
our script should respect it to signal regressions in return code too.

JerryScript-DCO-1.0-Signed-off-by: Csaba Osztrogonác oszi@inf.u-szeged.hu
robertsipka/jerryscript,bzsolt/jerryscript,zherczeg/jerryscript,bzsolt/jerryscript,bzsolt/jerryscript,dbatyai/jerryscript,akosthekiss/jerryscript,dbatyai/jerryscript,akosthekiss/jerryscript,zherczeg/jerryscript,akosthekiss/jerryscript,jerryscript-project/jerryscript,dbatyai/jerryscript,jerryscript-project/jerryscript,robertsipka/jerryscript,dbatyai/jerryscript,bzsolt/jerryscript,akosthekiss/jerryscript,jerryscript-project/jerryscript,zherczeg/jerryscript,bzsolt/jerryscript,jerryscript-project/jerryscript,robertsipka/jerryscript,akosthekiss/jerryscript,robertsipka/jerryscript,zherczeg/jerryscript,zherczeg/jerryscript,dbatyai/jerryscript,robertsipka/jerryscript,jerryscript-project/jerryscript,robertsipka/jerryscript