Oilpan: Fix stack copying release assert for ASan.

When we adjust the scope marker we can return the start of the stack
so we do not try to copy out from memory that is not part of the stack.
The release assert therefore needs to allow equality of the start of
stack and the scope marker.

R=timurrrr@chromium.org, vegorov@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/251523003

git-svn-id: svn://svn.chromium.org/blink/trunk@172500 bbb929c8-8fbe-4397-9dbb-9b2b20218538