SECURITY: Don't cache when a call could autocreate

Fixes for action=raw (used when sites include other site's javascript),
and stashed images.

Bug: 53032
Change-Id: I8f915f6a4756f750c74d9ee9bec58f7ba6c0c827
(cherry picked from commit 636c64482dc740e05b3a114927655a62acd1eca6)