Enable slimming paint by default (for trybots only)

Source/core/paint/LayoutObjectDrawingRecorderTest.cpp

 // Copyright 2014 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 "config.h"
 #include "core/paint/LayoutObjectDrawingRecorder.h"
 
 #include "core/layout/LayoutTestHelper.h"
 #include "core/layout/LayoutView.h"
 #include "core/paint/DeprecatedPaintLayer.h"
@@ skipping 21 matching lines @@
 
         RenderingTest::SetUp();
         enableCompositing();
 
         m_layoutView = document().view()->layoutView();
         ASSERT_TRUE(m_layoutView);
     }
 
     virtual void TearDown() override
     {
-        RuntimeEnabledFeatures::setSlimmingPaintEnabled(false);
+        // RuntimeEnabledFeatures::setSlimmingPaintEnabled(false);
     }
 
     LayoutView* m_layoutView;
 };
 
 namespace {
 
 void drawNothing(GraphicsContext& context, const LayoutView& layoutView, PaintPhase phase, const FloatRect& bound)
 {
     LayoutObjectDrawingRecorder drawingRecorder(context, layoutView, phase, bound);
@@ skipping 63 matching lines @@
     EXPECT_TRUE(isCached(newDisplayItemsBeforeUpdate()[0]));
     EXPECT_TRUE(isCached(newDisplayItemsBeforeUpdate()[1]));
     rootDisplayItemList().commitNewDisplayItems();
     EXPECT_EQ((size_t)2, rootDisplayItemList().displayItems().size());
     EXPECT_TRUE(isDrawing(rootDisplayItemList().displayItems()[0]));
     EXPECT_TRUE(isDrawing(rootDisplayItemList().displayItems()[1]));
 }
 
 } // namespace
 } // namespace blink