[webkit-reviews] review requested: [Bug 33150] Do not render the full frame when there is some elements with fixed positioning : [Attachment 47964] Repaint only the invalidated area after scrolling

[bugzilla-daemon at webkit.org]

Benjamin Poulain <benjamin.poulain at nokia.com> has asked  for review:
Bug 33150: Do not render the full frame when there is some elements with fixed
positioning
https://bugs.webkit.org/show_bug.cgi?id=33150

Attachment 47964: Repaint only the invalidated area after scrolling
https://bugs.webkit.org/attachment.cgi?id=47964&action=review

------- Additional Comments from Benjamin Poulain <benjamin.poulain at nokia.com>
Update the patch after discussions with Dave Hyatt on IRC.

As a side note: m_fixedObjectCount is only used for disabling blitting on Mac.
The platforms using FrameView always go to scrollContentsFastPath() and figure
if the number of fixed rects is higher than the threshold. I guess I could
cache the result of this computation until the render tree is invalidated, but
I don't think this computation is an issue in front of the time spent in
rendering.