commit dc0f408a961b6ce4e7631e06031bbfe1d8d7bcec
author kkinnunen <kkinnunen@nvidia.com> Mon Jan 26 08:14:26 2015
committer Commit bot <commit-bot@chromium.org> Mon Jan 26 08:14:26 2015
tree 0c039bb8fd3ea59d89a3d5fd088af5404f1dca72
parent 5c1dad7c751b7fa5a6291a15af3cfabb06808cba

Fold alpha to the inner savelayer in savelayer-savelayer-restore patterns

Fold alpha to the inner savelayer in savelayer-savelayer-restore
patterns such as this:

  SaveLayer (non-opaque)
    Save
      ClipRect
      SaveLayer
      Restore
    Restore
  Restore

Current blink generates these for example for SVG content such as this:

<path style="opacity:0.5 filter:url(#blur_filter)"/>

The outer save layer is due to the opacity and the inner one is due to
blur filter being implemented with picture image filter.

Reduces layers in desk_carsvg.skp testcase from 115 to 78.

BUG=skia:3119

Review URL: https://codereview.chromium.org/835973005