Add html/canvas directory to WebCore include paths, because it was added upstream.
Add html/canvas directory to WebCore include paths, because it was added upstream.

TBR=jorlow
BUG=none
TEST=none

Review URL: http://codereview.chromium.org/164233

git-svn-id: http://src.chromium.org/svn/trunk/src@22881 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 55302a4a997246cce755373b2f853ccc178101b1
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser