Revert of Only promote opaque scrollers which are stacking contexts.

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

Index: third_party/WebKit/Source/core/paint/PaintLayerScrollableAreaTest.cpp
diff --git a/third_party/WebKit/Source/core/paint/PaintLayerScrollableAreaTest.cpp b/third_party/WebKit/Source/core/paint/PaintLayerScrollableAreaTest.cpp
index 7678aa3e6b99335d95182f37b897e04590220430..4b393489fdef498eba1acc122bdfb02aa4ea55ed 100644
--- a/third_party/WebKit/Source/core/paint/PaintLayerScrollableAreaTest.cpp
+++ b/third_party/WebKit/Source/core/paint/PaintLayerScrollableAreaTest.cpp
@@ -156,14 +156,13 @@
   EXPECT_FALSE(canPaintBackgroundOntoScrollingContentsLayer("scroller16"));
 }
 
-TEST_F(PaintLayerScrollableAreaTest, OpaqueContainedLayersPromoted) {
+TEST_F(PaintLayerScrollableAreaTest, OpaqueLayersPromoted) {
   RuntimeEnabledFeatures::setCompositeOpaqueScrollersEnabled(true);
 
   setBodyInnerHTML(
       "<style>"
-      "#scroller { overflow: scroll; height: 200px; width: 200px; "
-      "contain: paint; background: white local content-box; "
-      "border: 10px solid rgba(0, 255, 0, 0.5); }"
+      "#scroller { overflow: scroll; height: 200px; width: 200px; background: "
+      "white local content-box; border: 10px solid rgba(0, 255, 0, 0.5); }"
       "#scrolled { height: 300px; }"
       "</style>"
       "<div id=\"scroller\"><div id=\"scrolled\"></div></div>");
@@ -178,36 +177,6 @@
   EXPECT_TRUE(paintLayer->graphicsLayerBacking());
   ASSERT_TRUE(paintLayer->graphicsLayerBackingForScrolling());
   EXPECT_TRUE(paintLayer->graphicsLayerBackingForScrolling()->contentsOpaque());
-}
-
-// Tests that we don't promote scrolling content which would not be contained.
-// Promoting the scroller would also require promoting the positioned div
-// which would lose subpixel anti-aliasing due to its transparent background.
-TEST_F(PaintLayerScrollableAreaTest, NonContainedLayersNotPromoted) {
-  RuntimeEnabledFeatures::setCompositeOpaqueScrollersEnabled(true);
-
-  setBodyInnerHTML(
-      "<style>"
-      "#scroller { overflow: scroll; height: 200px; width: 200px; "
-      "background: white local content-box; "
-      "border: 10px solid rgba(0, 255, 0, 0.5); }"
-      "#scrolled { height: 300px; }"
-      "#positioned { position: relative; }"
-      "</style>"
-      "<div id=\"scroller\">"
-      "  <div id=\"positioned\">Not contained by scroller.</div>"
-      "  <div id=\"scrolled\"></div>"
-      "</div>");
-  document().view()->updateAllLifecyclePhases();
-
-  EXPECT_TRUE(RuntimeEnabledFeatures::compositeOpaqueScrollersEnabled());
-  Element* scroller = document().getElementById("scroller");
-  PaintLayer* paintLayer =
-      toLayoutBoxModelObject(scroller->layoutObject())->layer();
-  ASSERT_TRUE(paintLayer);
-  EXPECT_FALSE(paintLayer->needsCompositedScrolling());
-  EXPECT_FALSE(paintLayer->graphicsLayerBacking());
-  EXPECT_FALSE(paintLayer->graphicsLayerBackingForScrolling());
 }
 
 TEST_F(PaintLayerScrollableAreaTest, TransparentLayersNotPromoted) {
@@ -217,7 +186,7 @@
       "<style>"
       "#scroller { overflow: scroll; height: 200px; width: 200px; background: "
       "rgba(0, 255, 0, 0.5) local content-box; border: 10px solid rgba(0, 255, "
-      "0, 0.5); contain: paint; }"
+      "0, 0.5); }"
       "#scrolled { height: 300px; }"
       "</style>"
       "<div id=\"scroller\"><div id=\"scrolled\"></div></div>");
@@ -239,7 +208,7 @@
   setBodyInnerHTML(
       "<style>"
       "#scroller { overflow: scroll; height: 200px; width: 200px; background: "
-      "white local content-box; contain: paint; }"
+      "white local content-box; }"
       "#scrolled { height: 300px; }"
       "</style>"
       "<div id=\"scroller\"><div id=\"scrolled\"></div></div>");
@@ -270,7 +239,7 @@
   setBodyInnerHTML(
       "<style>"
       "#scroller { overflow: scroll; height: 200px; width: 200px; background: "
-      "rgba(255,255,255,0.5) local content-box; contain: paint; }"
+      "rgba(255,255,255,0.5) local content-box; }"
       "#scrolled { height: 300px; }"
       "</style>"
       "<div id=\"scroller\"><div id=\"scrolled\"></div></div>");
@@ -304,7 +273,7 @@
   setBodyInnerHTML(
       "<style>"
       "#scroller { overflow: scroll; height: 200px; width: 200px; background: "
-      "white local content-box; contain: paint; }"
+      "white local content-box; }"
       "#scrolled { height: 300px; }"
       "</style>"
       "<div id=\"parent\">"
@@ -358,7 +327,7 @@
   setBodyInnerHTML(
       "<style>"
       "#scroller { overflow: scroll; height: 200px; width: 200px; background: "
-      "white local content-box; contain: paint; }"
+      "white local content-box; }"
       "#scrolled { height: 300px; }"
       "</style>"
       "<div id=\"parent\">"