Update WebViewImpl::contentsPreferredMinimumSize to be agnostic to the scrolling element

Source/web/WebViewImpl.cpp

Index: Source/web/WebViewImpl.cpp
diff --git a/Source/web/WebViewImpl.cpp b/Source/web/WebViewImpl.cpp
index 6eb50580c2bf29e160f74b222c7187075b105a8d..8d147685fef696d9853bd60e5eb589dd6fdee550 100644
--- a/Source/web/WebViewImpl.cpp
+++ b/Source/web/WebViewImpl.cpp
@@ -3397,12 +3397,12 @@ IntSize WebViewImpl::contentsSize() const
 WebSize WebViewImpl::contentsPreferredMinimumSize()
 {
     Document* document = m_page->mainFrame()->isLocalFrame() ? m_page->deprecatedLocalMainFrame()->document() : 0;
-    if (!document || !document->layoutView() || !document->documentElement())
+    if (!document || !document->layoutView() || !document->documentElement() || !document->documentElement()->layoutBox())
         return WebSize();
 
     layout();
     int widthScaled = document->layoutView()->minPreferredLogicalWidth().round(); // Already accounts for zoom.
-    int heightScaled = static_cast<int>((document->documentElement()->scrollHeight() * zoomLevelToZoomFactor(zoomLevel())) + 0.5); // +0.5 to round rather than truncating
+    int heightScaled = document->documentElement()->layoutBox()->scrollHeight().round();
     return IntSize(widthScaled, heightScaled);
 }