SimpleCache: remove a check invalidated by optimistic create-doom

Cq-Include-Trybots: master.tryserver.chromium.android:android_cronet_tester;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: Iec06439e965046a8173d2a7aa23fd66728792a68
Reviewed-on: https://chromium-review.googlesource.com/751281
Commit-Queue: Maks Orlovich <morlovich@chromium.org>
Reviewed-by: Julia Tuttle <juliatuttle@chromium.org>
Cr-Commit-Position: refs/heads/master@{#516046}
2 files changed