mkvparser: Segment::PreloadCluster asserts to error checks.
mkvparser: Segment::PreloadCluster asserts to error checks.

Change-Id: I3a2e2226f30ee047f96f5136c52e4cb9081d42c8

webmproject/libwebm,zofuthan/libwebm,webmproject/libwebm,felipebetancur/libwebm,felipebetancur/libwebm,zofuthan/libwebm,webmproject/libwebm