Signed left shift operations are undefined in C. Add constants for the minimum/maximum integer value which are already shifted. Technically, the constant for the shifted maximum value is not required, adding it for consistency/increased readability.
The bug was detected by -Wshift-negative-value both with GCC 6.x and Clang.
This fixes#1174.
JerryScript-DCO-1.0-Signed-off-by: Tilmann Scheller t.scheller@samsung.com