Don't squash layers that have a clip or overflow clip.

Source/core/rendering/compositing/RenderLayerCompositor.cpp

Index: Source/core/rendering/compositing/RenderLayerCompositor.cpp
diff --git a/Source/core/rendering/compositing/RenderLayerCompositor.cpp b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
index 1e92f38a35e21e1bef1057fc4fecf2b903285822..092d4a0507bd678609a786fae9dee418ad9ccb27 100644
--- a/Source/core/rendering/compositing/RenderLayerCompositor.cpp
+++ b/Source/core/rendering/compositing/RenderLayerCompositor.cpp
@@ -710,6 +710,11 @@ bool RenderLayerCompositor::canSquashIntoCurrentSquashingOwner(const RenderLayer
     if (layer->renderer()->clippingContainer() != squashingLayer.renderer()->clippingContainer())
         return false;
 
+    // FIXME: this seems to be overly aggressive. clipsCompositingDescendants() should suffice. However, it does not fix all testcases,
+    // in particular crbug.com/366101.
+    if (layer->renderer()->hasClipOrOverflowClip())
+        return false;
+
     if (layer->scrollsWithRespectTo(&squashingLayer))
         return false;