Fix hterm's last line disappearing depending on the zoom level
Fix hterm's last line disappearing depending on the zoom level

We need to average the height of the character the same way we average the width to
avoid rounding errors.

BUG=chromium:633924
TEST=mkdeps.sh, mkzip.sh --nopromote and then load it on the device and try seq 1000 several times. The last line shouldn't disappear

Change-Id: I0d0dfe749a6e02f8023e2709c7222446d6e136e0
Reviewed-on: https://chromium-review.googlesource.com/385075
Reviewed-by: Rob Ginda <4419ac4e35d191308e944202d542b192188656d1@chromium.org>
Tested-by: Rob Ginda <4419ac4e35d191308e944202d542b192188656d1@chromium.org>

chromium/hterm,chromium/hterm,chromium/hterm,chromium/hterm