Ensure canvas virtual test suites remain orthogonal
Ensure canvas virtual test suites remain orthogonal

Future changes to default settings and heuristics may affect the use
of display list canvas in layout test executions. To make sure that
the test coverage provided by the gpu and display_list_2d_canvas suites
remains unchanged and orthogonal, we must forcibly disable and enable
display lists in the test suites.

BUG=386601

Review URL: https://codereview.chromium.org/752593002

git-svn-id: bf5cd6ccde378db821296732a091cfbcf5285fbd@185809 bbb929c8-8fbe-4397-9dbb-9b2b20218538

primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs,primiano/blink-gitcs