morphic: fix CanvasMorph resizing, add pixelRatio
morphic: fix CanvasMorph resizing, add pixelRatio

LivelyKernel/LivelyKernel,NikolaySuslov/LivelyKernel,NikolaySuslov/LivelyKernel,NikolaySuslov/LivelyKernel,LivelyKernel/LivelyKernel,pascience/LivelyKernel,pascience/LivelyKernel,pascience/LivelyKernel,LivelyKernel/LivelyKernel