Fix compilation and ui_unittests with float transforms

This change also cleans up the use of gfx::Transform::get/setDouble
(in favor of get/set) at callsites to prepare for changing SkMScalar
from double to float.

BUG=269817

Originally Committed/Reverted: https://src.chromium.org/viewvc/chrome?view=rev&revision=224725

Review URL: https://chromiumcodereview.appspot.com/23811009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@225130 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 225130