[#156116063] Fix Bug: closed Sage Modeler graphs reappear...
[#156116063] Fix Bug: closed Sage Modeler graphs reappear...

Bug has been present since commit 6ac4763, build 0373.
Ultimate cause, though is a delete component model which was
accessing a SC property of the document object incorrectly.

concord-consortium/codap,concord-consortium/codap,concord-consortium/codap,concord-consortium/codap,concord-consortium/codap