remove the weak_ptrs on destruction too
remove the weak_ptrs on destruction too

Change-Id: I65f5867c41417539a70eef15754988d9931394a4

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core