Revert "Cache image scalable promises by filename"

Caused bug 65314.

This reverts commit 97bc12a4212d9681f5e0b0e28e5bc038b7eeca4d.

Bug: 65314
Change-Id: Iaca46e5458fbc44446cc92e7241dd24d7de883d8
Merge "Revert "Cache image scalable promises by filename""