cc: Make corner cases of tile priority computation more simple.
cc: Make corner cases of tile priority computation more simple.

This changes tile priority computation so that max tile priority bin has
an effect only on priority bin but not on distance to visible. This
affects only tiles on layers which do not have valid tile priorities.

Review URL: https://codereview.chromium.org/1154503002

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#331086}

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