Fix PaintLayer::compositingContainer for self-painting non-stacked layers

third_party/WebKit/Source/core/paint/PaintLayerTest.cpp

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/paint/PaintLayer.h"
 
 #include "core/html/HTMLIFrameElement.h"
 #include "core/layout/LayoutBoxModelObject.h"
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
@@ skipping 608 matching lines @@
           ->layer();
 
   // enclosingLayerWithCompositedLayerMapping is not needed or applicable to
   // SPv2.
   if (!RuntimeEnabledFeatures::slimmingPaintV2Enabled()) {
     EXPECT_EQ(compositedContainer,
               target->enclosingLayerWithCompositedLayerMapping(ExcludeSelf));
   }
 }
 
+TEST_P(PaintLayerTest, CompositingContainerSelfPaintingNonStackedFloat) {
+  setBodyInnerHTML(
+      "<div id='container' style='position: relative'>"
+      "  <span id='span' style='opacity: 0.9'>"
+      "    <div id='target' style='columns: 1; float: left'></div>"
+      "  </span>"
+      "</div>");
+
+  // The target layer is self-painting, but not stacked.
+  PaintLayer* target =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("target"))->layer();
+  EXPECT_TRUE(target->isSelfPaintingLayer());
+  EXPECT_FALSE(target->stackingNode()->isStacked());
+
+  PaintLayer* span =
+      toLayoutBoxModelObject(getLayoutObjectByElementId("span"))->layer();
+  EXPECT_EQ(span, target->compositingContainer());
+}
+
 }  // namespace blink