CSS Shape renders incorrectly when scrolling

While rendering, scrollOffset was taken into account. This lead to wrong points for creation of the shape.

Patch proposes removing of scrollOffset to avoid the behavior.

BUG=392857
R=pfeldman
TEST=Circle should render similarly, inspite of a scroll.

Review URL: https://codereview.chromium.org/396803010

git-svn-id: svn://svn.chromium.org/blink/trunk@178460 bbb929c8-8fbe-4397-9dbb-9b2b20218538