Enable compositing of scrolling content on low-DPI when LCD text will be maintained

third_party/WebKit/LayoutTests/fast/block/child-with-auto-margin-rtl-body-expected.html

 <style>
 body {
     direction: rtl;
 }
 .outer {
     height: 500px;
     overflow: auto;
+    background: green;
 }
 .inner {
     height: 1000px;
     background: green;
 }
 </style>
 <div class="outer">
     <div class="inner">
     </div>
 </div>
 <p>crbug.com/541574: Calculate the correct left offset for children in an rtl context. There should be no red.</p>