Bug 1713769 - Ensure extracting SkImage subset is actually successful. r=gfx-reviewers,jrmuizel

If ExtractSubset fails on an SkImage, we may accidentally call image->makeShader
with a null image below that. We need to bail out in that case so that we don't
do that.

Differential Revision: https://phabricator.services.mozilla.com/D128667

gfx/2d/DrawTargetSkia.cpp

@@ -573,6 +573,10 @@ static void SetPaintPattern(SkPaint& aPaint, const Pattern& aPattern,
 
       if (!pat.mSamplingRect.IsEmpty()) {
         image = ExtractSubset(image, pat.mSamplingRect);
+        if (!image) {
+          aPaint.setColor(SK_ColorTRANSPARENT);
+          break;
+        }
         mat.preTranslate(pat.mSamplingRect.X(), pat.mSamplingRect.Y());
       }