[RLS] Don't create PaintLayerCompositor layers.

third_party/WebKit/LayoutTests/compositing/layer-tree-expected.txt

+{
+  "name": "Root Transform Layer",
+  "children": [
+    {
+      "name": "Inner Viewport Container Layer",
+      "bounds": [800, 600],
+      "children": [
+        {
+          "name": "Overscroll Elasticity Layer",
+          "children": [
+            {
+              "name": "Page Scale Layer",
+              "children": [
+                {
+                  "name": "Inner Viewport Scroll Layer",
+                  "bounds": [800, 600],
+                  "children": [
+                    {
+                      "name": "Frame Overflow Controls Host Layer",
+                      "bounds": [800, 600],
+                      "children": [
+                        {
+                          "name": "Frame Clipping Layer",
+                          "bounds": [780, 580],
+                          "children": [
+                            {
+                              "name": "Frame Scrolling Layer",
+                              "children": [
+                                {
+                                  "name": "Content Root Layer",
+                                  "bounds": [1200, 900],
+                                  "children": [
+                                    {
+                                      "name": "LayoutView #document",
+                                      "bounds": [1200, 900],
+                                      "contentsOpaque": true,
+                                      "drawsContent": true
+                                    }
+                                  ]
+                                }
+                              ]
+                            }
+                          ]
+                        }
+                      ]
+                    }
+                  ]
+                }
+              ]
+            }
+          ]
+        },
+        {
+          "name": "Frame Horizontal Scrollbar Layer",
+          "position": [0, 580],
+          "bounds": [780, 20],
+          "drawsContent": true
+        },
+        {
+          "name": "Frame Vertical Scrollbar Layer",
+          "position": [780, 0],
+          "bounds": [20, 580],
+          "drawsContent": true
+        },
+        {
+          "name": "Frame Scroll Corner Layer",
+          "position": [780, 580],
+          "bounds": [20, 20],
+          "drawsContent": true
+        }
+      ]
+    }
+  ]
+}
+