Merge "webview: deflake testRequestImageRef." into oreo-mr1-cts-dev am: 14d50d7d88

Original change: https://android-review.googlesource.com/c/platform/cts/+/1573300

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I985c85cf27cb7b7da91b66e8a0e56ed43a4bc0c0