Fixing RecordingImageBufferSurface to stay in display list mode

This fix makes RecordingImageBufferSurface track the initial
stack level of the SkPicture recording canvas to avoid falsely
rejecting canvases from display list mode due to state present
on the stack

BUG=396800
TEST=RecordingImageBufferSurfaceTest platform unit tests
NOTRY=true

Review URL: https://codereview.chromium.org/412993004

git-svn-id: svn://svn.chromium.org/blink/trunk@178804 bbb929c8-8fbe-4397-9dbb-9b2b20218538