Bug 542605. Use EXTEND_PAD_EDGE when painting svg images. r=jwatt

This was part of the cairo update, but I'm doing it separately to
minimize the amount of unrelated change.

layout/svg/base/src/nsSVGImageFrame.cpp

@@ -257,6 +257,7 @@ nsSVGImageFrame::PaintSVG(nsSVGRenderState *aContext,
   if (thebesPattern) {
 
     thebesPattern->SetFilter(nsLayoutUtils::GetGraphicsFilterForFrame(this));
+    thebesPattern->SetExtend(gfxPattern::EXTEND_PAD_EDGE);
 
     gfxContext *gfx = aContext->GetGfxContext();