This patch adds support for sext, zext, trunc operations on i8, i16, i32 source operand types. Support for i1 source operand type will follow.

R=stichnot@chromium.org

Review URL: https://codereview.chromium.org/1948093002 .

Patch from Sagar Thakur <sagar.thakur@imgtec.com>.