Directly composited images are images: ASSERT that

Source/core/rendering/compositing/CompositedLayerMapping.cpp

Index: Source/core/rendering/compositing/CompositedLayerMapping.cpp
diff --git a/Source/core/rendering/compositing/CompositedLayerMapping.cpp b/Source/core/rendering/compositing/CompositedLayerMapping.cpp
index 1924a3268a64f8c9bdbe32b0526ef477db51102e..9dcc29b989d32463a201e0214ca07f6174113355 100644
--- a/Source/core/rendering/compositing/CompositedLayerMapping.cpp
+++ b/Source/core/rendering/compositing/CompositedLayerMapping.cpp
@@ -457,7 +457,7 @@ bool CompositedLayerMapping::updateGraphicsLayerConfiguration()
 
     updateBackgroundColor();
 
-    if (isDirectlyCompositedImage())
+    if (renderer->isImage() && isDirectlyCompositedImage())
         updateImageContents();
 
     if (WebLayer* layer = platformLayerForPlugin(renderer)) {
@@ -1698,7 +1698,7 @@ bool CompositedLayerMapping::containsPaintedContent() const
     if (paintsIntoCompositedAncestor() || m_owningLayer.isReflection())
         return false;
 
-    if (isDirectlyCompositedImage())
+    if (renderer()->isImage() && isDirectlyCompositedImage())
         return false;
 
     RenderObject* renderObject = renderer();
@@ -1742,9 +1742,10 @@ bool CompositedLayerMapping::containsPaintedContent() const
 // that require painting. Direct compositing saves backing store.
 bool CompositedLayerMapping::isDirectlyCompositedImage() const
 {
-    RenderObject* renderObject = renderer();
+    ASSERT(renderer()->isImage());
 
-    if (!renderObject->isImage() || m_owningLayer.hasBoxDecorationsOrBackground() || renderObject->hasClip())
+    RenderObject* renderObject = renderer();
+    if (m_owningLayer.hasBoxDecorationsOrBackground() || renderObject->hasClip())
         return false;
 
     RenderImage* imageRenderer = toRenderImage(renderObject);
@@ -1761,7 +1762,7 @@ bool CompositedLayerMapping::isDirectlyCompositedImage() const
 
 void CompositedLayerMapping::contentChanged(ContentChangeType changeType)
 {
-    if ((changeType == ImageChanged) && isDirectlyCompositedImage()) {
+    if ((changeType == ImageChanged) && renderer()->isImage() && isDirectlyCompositedImage()) {
         updateImageContents();
         return;
     }
@@ -1791,6 +1792,8 @@ void CompositedLayerMapping::updateImageContents()
 
     // This is a no-op if the layer doesn't have an inner layer for the image.
     m_graphicsLayer->setContentsToImage(image);
+
+    // Prevent double-drawing: https://bugs.webkit.org/show_bug.cgi?id=58632
     updateDrawsContent();
 
     // Image animation is "lazy", in that it automatically stops unless someone is drawing