Fix heap buffer overflow in CPDF_SampledFunc::v_Call

This issue was caused by integer overflow in CPDF_SampledFunc::v_Call.
The root cause of this issue is that the content in the test pdf file
was damaged. The solution is to check whether an integer is overflow
before using it.

BUG=452455
R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/886953002
1 file changed