fix memory leak on pasting metafiles into writer
fix memory leak on pasting metafiles into writer

copying from mspaint to writer and then deleting the image in a loop will
eventually exhaust all memory.

regression since 004a29b9ac66f68af5ea12a2303a4b2be77d8145

Change-Id: I381285cda3823de7df0c1725a339943caf9536fe

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