Remove Android's existing layout test result files.

Most of these results were based on results created using DRT, and are no
longer relevant now that we're going to run tests using content_shell. Keep
a few media tests which have been added recently (r153818, r154314 and
r155769).

BUG=232044
TBR=dpranke

git-svn-id: svn://svn.chromium.org/blink/trunk@156932 bbb929c8-8fbe-4397-9dbb-9b2b20218538