Blob.cc: add some assertions for bad cases
Blob.cc: add some assertions for bad cases

fengzhyuan/visionworkbench,fengzhyuan/visionworkbench,AveRapina/visionworkbench,AveRapina/visionworkbench,DougFirErickson/visionworkbench,fengzhyuan/visionworkbench,fengzhyuan/visionworkbench,fengzhyuan/visionworkbench,DougFirErickson/visionworkbench,AveRapina/visionworkbench,fengzhyuan/visionworkbench,DougFirErickson/visionworkbench,fengzhyuan/visionworkbench,AveRapina/visionworkbench,DougFirErickson/visionworkbench,DougFirErickson/visionworkbench,DougFirErickson/visionworkbench,AveRapina/visionworkbench,AveRapina/visionworkbench