Update most LayoutTests to be agnostic to scrollTopLeftInterop mode

LayoutTests/compositing/rtl/rtl-fixed-overflow-scrolled.html

Index: LayoutTests/compositing/rtl/rtl-fixed-overflow-scrolled.html
diff --git a/LayoutTests/compositing/rtl/rtl-fixed-overflow-scrolled.html b/LayoutTests/compositing/rtl/rtl-fixed-overflow-scrolled.html
index 372ddef1df2a12e1c84cdc0145985a731af3c6cd..cd6faa4ca956c524e29fba028b1d12a3972b9798 100644
--- a/LayoutTests/compositing/rtl/rtl-fixed-overflow-scrolled.html
+++ b/LayoutTests/compositing/rtl/rtl-fixed-overflow-scrolled.html
@@ -45,7 +45,7 @@
         }
 
         // The far left coordinate of the document varies by window width.
-        var offset = document.body.clientWidth - document.body.scrollWidth + 1;
+        var offset = document.body.clientWidth - document.scrollingElement.scrollWidth + 1;
 
         window.setTimeout(function() {
             window.scrollTo(offset, 0);