Relax HTMLBodyElement's scrollTop/Left property set and get operations.

Source/core/page/UseCounter.cpp

Index: Source/core/page/UseCounter.cpp
diff --git a/Source/core/page/UseCounter.cpp b/Source/core/page/UseCounter.cpp
index 93bfa17917572ac19cf7baf895b48b2a7371ea75..f27e3f77f4df903bbb9c848358f4775a9fa269e4 100644
--- a/Source/core/page/UseCounter.cpp
+++ b/Source/core/page/UseCounter.cpp
@@ -676,6 +676,10 @@ String UseCounter::deprecationMessage(Feature feature)
     case EventReturnValue:
         return "event.returnValue is deprecated. Please use the standard event.preventDefault() instead.";
 
+    case ScrollTopBody:
+        return "body.scrollTop is deprecated in strict mode. Please use 'documentElement.scrollTop' if in strict mode and 'body.scrollTop' only if in quirks mode.";
+    case ScrollLeftBody:
+        return "body.scrollLeft is deprecated in strict mode. Please use 'documentElement.scrollLeft' if in strict mode and 'body.scrollLeft' only if in quirks mode.";
     // Features that aren't deprecated don't have a deprecation message.
     default:
         return String();