Fix count of elements in buffer

There can be one extra element at the end even if an entire stride doesn't fit.

BUG=
TEST=

Review URL: http://codereview.appspot.com/5401046

git-svn-id: https://angleproject.googlecode.com/svn/trunk@884 736b8ea6-26fd-11df-bfd4-992fa37f6226
2 files changed