fix (some) 64bit warnings -- size_t -> int

BUG=skia:
R=mtklein@google.com

Author: reed@google.com

Review URL: https://codereview.chromium.org/147053003

git-svn-id: http://skia.googlecode.com/svn/trunk@13178 2bbb7eff-a529-9590-31e7-b0007b416f81
14 files changed