Fixed ScriptGroup finalizer for old API

Bug: 28242626

ScriptGroup finalizer clears out the list of closures, which is
uninitialized for the old API.

Need to check null first, before accessing the list.

Change-Id: Ibf914e17a0878c8c561f823c5f6f6f6619594de1
(cherry picked from commit 07837d6dab331b1693aa3689223b4012012a7fad)
1 file changed