Replace all instances of 'clear' with 'pop's in conical gradient pdf impl, looks like the pdf spec doesn't support Postscript's 'clear' stack operator. Should fix some warnings on mac buildbots.
Replace all instances of 'clear' with 'pop's in conical gradient pdf impl, looks like the pdf spec doesn't support Postscript's 'clear' stack operator. Should fix some warnings on mac buildbots.

git-svn-id: e8541e15acce502a64c929015570ad1648e548cd@4521 2bbb7eff-a529-9590-31e7-b0007b416f81

mrobinson/skia,Cue/skia,mrobinson/skia,mrobinson/skia,metajack/skia,Cue/skia,Cue/skia,mrobinson/skia,mrobinson/skia,metajack/skia,Cue/skia,metajack/skia,metajack/skia