Fix GeneratedImage usage to respect Image's refcounting

[Eric Seidel (no email)]

Fix GeneratedImage usage to respect Image's refcounting

I found this while I was searching for the Image-related leak on ToT.

[Eric Seidel (no email)]

Created attachment 23067 [details]
Fix GeneratedImage to respect Image's refcounting

 WebCore/css/CSSGradientValue.cpp           |   11 ++++++-----
 WebCore/css/CSSImageGeneratorValue.cpp     |    7 +++----
 WebCore/css/CSSImageGeneratorValue.h       |    4 ++--
 WebCore/platform/graphics/GeneratedImage.h |   11 ++++++++---
 WebCore/rendering/style/RenderStyle.cpp    |    5 ++---
 WebCore/rendering/style/RenderStyle.h      |    4 ++--
 6 files changed, 23 insertions(+), 19 deletions(-)

[Eric Seidel (no email)]

I don't think this will fix any leaks seen on ToT, but it will prevent future crashes due to clients expecting Images to live as long as their refcount is non-zero. :)

[Eric Seidel (no email)]

I will add a ChangeLog when I land.

[Eric Seidel (no email)]

For example, if somehow this image could be used as a tile to a Pattern, it's possible that this could be made to crash on ToT.  I'm not really sure how to use GeneratedImages, but if one can get an HTMLImageElement to use one so that a CanvasPattern can end up creating a Pattern using a GeneratedImage, then the following code should crash webkit:

var canvas = document.getElementById("canvas");
var img = document.getElementById("imgUsingGeneratedImage");
var ctx = canvas.getContext("2d");
var pattern = ctx.createPattern(image);
img.parentNode.removeChild(img);
ctx.fillStyle = pattern;
ctx.fillRect(0, 0, 100, 100);

[Dave Hyatt]

Comment on attachment 23067 [details]
Fix GeneratedImage to respect Image's refcounting

r=me