Fix valgrind error caused by NONE_FRAME in ref list
Fix valgrind error caused by NONE_FRAME in ref list

This error was reintroduced by
in an attempt to fix 91eb798b8fdac2ae7fde04a308a04c8d73ebc393
a mismatch introduced by the original bug fix at
72e2e982ee72080418e8c26adb70e34b4a2c6cb0.

BUG=aomedia:412

Change-Id: Iffc16fe0f5f3f953b0604a7cf56433350673338c

GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom,GrokImageCompression/aom