cc: Don't mark a previous low res as LOW_RESOLUTION during animation.

cc: Don't mark a previous low res as LOW_RESOLUTION during animation.

This patch ensures that we don't mark the previous low resolution
tiling as a LOW_RESOLUTION tiling, since it really isn't a low res,
it's some other scale.

This is a speculative fix for the listed bug, since if we end up
in a situation where we have a low res at a higher scale than high
res, the eviction iterator crash on iteration of "between low and
high res" stage (The range will be malformed with end < start).

BUG=423240
R=danakj, enne

Review URL: https://codereview.chromium.org/653243002

Cr-Commit-Position: refs/heads/master@{#299606}