Array constructor using ecma_lenght_t for length argument

[dbatyai]

Currently, the array constructor takes ecma_length_t, which is an uint16, as it's length argument, even though the length of an array can be an uint32. The two should be compatible, so we should either change ecma_length_t to be uint32, or change the array constructor to take uint32 for length.

[galpeter]

IMHO this can be closed now, as the ecma_length_t is now a uint32_t.