JS: ensure we clear the scratch buffer references
JS: ensure we clear the scratch buffer references

When resetting the EventTree, make sure we do not hold on to any references to
EventNodes in the scratch buffer.

Signed-off-by: Harvey Harrison <eadbd6b462bf3c97df0300a934c12bc2e5d1fe51@ausenco.com>

jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim,jaamsim/jaamsim