DevTools: untangle paint profiler for better reuse

Source/devtools/front_end/layersPanel.css

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 65 matching lines @@
 .layer-details-view .scroll-rect.active {
     background-color: rgba(100, 100, 100, 0.2);
 }
 
 .paint-profiler-view canvas {
     z-index: 200;
     opacity: 0.8;
     background-color: white;
 }
 
-.paint-profiler-view .split-view-main {
+.paint-profiler-view {
     overflow: hidden;
 }
 
 .paint-profiler-view .overview-grid-dividers-background,
 .paint-profiler-view .overview-grid-window {
     bottom: 0;
     height: auto;
 }
 
 .paint-profiler-view .overview-grid-window-resizer {
     z-index: 2000;
 }