Move some non-unittest files to compositor_test_support


BUG=NONE

Review URL: https://codereview.chromium.org/147033003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247903 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247903
Move webkit/child/webkitplatformsupport_child_impl to content/

BUG=338338

Review URL: https://codereview.chromium.org/148333009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@247904 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 247904