Add handling for Skia's SkPath::intersect's return value

content/shell/renderer/test_runner/mock_web_theme_engine.cc

Index: content/shell/renderer/test_runner/mock_web_theme_engine.cc
diff --git a/content/shell/renderer/test_runner/mock_web_theme_engine.cc b/content/shell/renderer/test_runner/mock_web_theme_engine.cc
index 5ad404ee3626bda948ca8c5456c64161fa8294a9..64480708fa779b1c2f4f259c6080403811c3098b 100644
--- a/content/shell/renderer/test_runner/mock_web_theme_engine.cc
+++ b/content/shell/renderer/test_runner/mock_web_theme_engine.cc
@@ -628,7 +628,9 @@ void MockWebThemeEngine::paint(blink::WebCanvas* canvas,
                 extraParams->progressBar.valueRectHeight);
         }
 
-        tofill.intersect(irect, tofill);
+        if (!tofill.intersect(irect)) {
+            tofill.setEmpty();
+        }
         paint.setColor(edgeColor);
         paint.setStyle(SkPaint::kFill_Style);
         canvas->drawIRect(tofill, paint);