Cleanup: Get rid of make_isize() function from gm.h.

This helper function is not necessary.

The same thing can be achieved by using SkISize::Make() provided by
SkTSize API.

BUG=skia:2645
TEST=make dm && out/Debug/dm
R=robertphillips@google.com, reed@google.com

Author: tfarina@chromium.org

Review URL: https://codereview.chromium.org/326523002
97 files changed