Update most LayoutTests to be agnostic to scrollTopLeftInterop mode

LayoutTests/fast/dom/window-scroll-scaling.html

Index: LayoutTests/fast/dom/window-scroll-scaling.html
diff --git a/LayoutTests/fast/dom/window-scroll-scaling.html b/LayoutTests/fast/dom/window-scroll-scaling.html
index 067304012d2a3efcabc7558eeff73bb7388232d0..d0da529934bd012b7eaf03cbb59e9b6cb33c75b8 100644
--- a/LayoutTests/fast/dom/window-scroll-scaling.html
+++ b/LayoutTests/fast/dom/window-scroll-scaling.html
@@ -19,8 +19,8 @@
         body.style["width"] = window.innerWidth + 100 + "px";
         body.style["height"] = window.innerHeight + 100 + "px";

[tdresser, 2015/05/19 13:53:11]

Is this correct?
Should we be setting the size of the scrollingElement, or the body?

[Rick Byers, 2015/05/20 15:10:24]

Either would work, but since this test is explicitly testing quirks mode
behavior I'll revert this back to just 'body'.  Technically the test is equally
valid in non-quirks mode if it used scrollingElement but I'm not aiming to
increase any test coverage with this CL so let's just keep it as-is.

There may be some other cases where I unnecessarily updated quirks-mode tests to
use scrollingElement (since mostly this was a bulk-refactor), but I don't think
there's much downside (they're still correct) so I'm not planning on looking
explicitly for such cases.

 
-        var originalScrollWidth = body.scrollWidth;
-        var originalScrollHeight = body.scrollHeight;
+        var originalScrollWidth = document.scrollingElement.scrollWidth;
+        var originalScrollHeight = document.scrollingElement.scrollHeight;
 
         var scale = 1.1;
         if (window.eventSender)
@@ -28,11 +28,11 @@
 
         // As we have increased the scale factor, the innerWidth will be less
         // as fewer CSS pixels will be rendered in the same viewport, so
-        // body.scrollWidth (scrollHeight) will still be measuring the document
+        // scrollingElement.scrollWidth (scrollHeight) will still be measuring the document

[tdresser, 2015/05/19 13:53:11]

nit: scrollingElement->document.scrollingElement

         // content width (height).
 
-        shouldBe("body.scrollWidth", "originalScrollWidth");
-        shouldBe("body.scrollHeight", "originalScrollHeight");
+        shouldBe("document.scrollingElement.scrollWidth", "originalScrollWidth");
+        shouldBe("document.scrollingElement.scrollHeight", "originalScrollHeight");
     </script>
 </body>
 </html>