ScrollTopLeftInterop should not be marked experimental

LayoutTests/http/tests/navigation/resources/frame-with-anchor.html

Index: LayoutTests/http/tests/navigation/resources/frame-with-anchor.html
diff --git a/LayoutTests/http/tests/navigation/resources/frame-with-anchor.html b/LayoutTests/http/tests/navigation/resources/frame-with-anchor.html
index 9417e0b7bc6dc3c862a7996b1a93b354545b148e..4253f818024d898737cc90cf57ec01e53614a46a 100644
--- a/LayoutTests/http/tests/navigation/resources/frame-with-anchor.html
+++ b/LayoutTests/http/tests/navigation/resources/frame-with-anchor.html
@@ -14,10 +14,10 @@
           shouldBeTrue('document.documentElement.offsetHeight > document.documentElement.clientHeight');
           
           // We should be scrolled at least a little bit
-          shouldBeTrue('document.documentElement.scrollTop > 0');
+          shouldBeTrue('document.body.scrollTop > 0');
           
           // And the bottom of the viewable area should be at least 2000 pixels from the top, due to the spacer element above.
-          shouldBeTrue('document.documentElement.scrollTop + document.documentElement.clientHeight > 2000');
+          shouldBeTrue('document.body.scrollTop + document.body.clientHeight > 2000');
           
           finishJSTest();          
       }, 0);