Bug 1167356 - Check return value of DataSourceSurface::Map in RasterImage::CopyFrame. r=Bas

image/RasterImage.cpp

@@ -686,8 +686,11 @@ RasterImage::CopyFrame(uint32_t aWhichFrame, uint32_t aFlags)
   }
 
   DataSourceSurface::MappedSurface mapping;
-  DebugOnly<bool> success =
-    surf->Map(DataSourceSurface::MapType::WRITE, &mapping);
+  if (!surf->Map(DataSourceSurface::MapType::WRITE, &mapping)) {
+    gfxCriticalError() << "RasterImage::CopyFrame failed to map surface";
+    return nullptr;
+  }
+
   NS_ASSERTION(success, "Failed to map surface");
   RefPtr<DrawTarget> target =
     Factory::CreateDrawTargetForData(BackendType::CAIRO,