Move Platform{Canvase,Device}Mac.cpp from the Mac remove-from-input list (for things to be ported) to the add-to-input file list.
Move Platform{Canvase,Device}Mac.cpp from the Mac remove-from-input
list (for things to be ported) to the add-to-input file list.

These ended up on the wrong list because we had really confusing
logic down at the bottom of SConscript.port, with multiple lists
and redundant conditional checks.  So refactor the bottom to
collect all platform-specific logic behind single checks for
the platform, rearrange and rename lists to (hopefully) make it
easier to identify what goes where, and add comments.
Review URL: http://codereview.chromium.org/11361

git-svn-id: http://src.chromium.org/svn/trunk/src@5889 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 1e373f5f8d03b8756a7f390118811874d7afaecb
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