Revert "buffered: Defer ReplacePixels when possible"
Revert "buffered: Defer ReplacePixels when possible"

This reverts commit 1395ab5e846c55b5434de4d0515cba6083951d4d.

Reason: This increases the number of ReplacePixels aggressively.

hajimehoshi/ebiten,hajimehoshi/ebiten