Checking for simple image layer optimisation

# Image optimisation in layers

In order to run this test you should enable the debugging options that indicate what type of compositing layer is being used.

    defaults write com.apple.Safari WebCoreLayerRepaintCounter -bool yes
    defaults write com.apple.Safari WebCoreLayerBorders -bool yes

Directly composited image layers will have a yellow border and no repaint counter.

Basic image - no style - can be directly composited

5px blue border - can NOT be directly composited

margin - can NOT be directly composited

solid background - can be directly composited

background image - can NOT be directly composited

rotated but otherwise no style - can be directly composited