It's not neccessary to proceed rendering of the object and it's child, if the content gets completely clipped away by a mask or if it has an bogus or one-dimensional filter.
Created attachment 45530 [details] stop rendering of object if SVG mak clips content away patch
Created attachment 45533 [details] stop rendering of object if SVG mak clips content away fixes a bug in SVGResourceMasker
style-queue ran check-webkit-style on attachment 45533 [details] without any errors.
Comment on attachment 45533 [details] stop rendering of object if SVG mak clips content away Excellent job, r=me.
landed in r52584.