Introduce isHTMLHtmlElement and toHTMLHtmlElement

Source/core/css/resolver/StyleResolver.cpp

Index: Source/core/css/resolver/StyleResolver.cpp
diff --git a/Source/core/css/resolver/StyleResolver.cpp b/Source/core/css/resolver/StyleResolver.cpp
index 73bc77ba1b99a34e70e16e6efa8eaa560ae4419e..cc6507d89385fdbf7ef4b07324d351464858f6ac 100644
--- a/Source/core/css/resolver/StyleResolver.cpp
+++ b/Source/core/css/resolver/StyleResolver.cpp
@@ -77,6 +77,7 @@
 #include "core/dom/Text.h"
 #include "core/dom/WebCoreMemoryInstrumentation.h"
 #include "core/dom/shadow/ShadowRoot.h"
+#include "core/html/HTMLHtmlElement.h"
 #include "core/html/HTMLIFrameElement.h"
 #include "core/html/HTMLInputElement.h"
 #include "core/html/HTMLOptGroupElement.h"
@@ -1551,7 +1552,7 @@ void StyleResolver::adjustRenderStyle(RenderStyle* style, RenderStyle* parentSty
     // Call setStylesForPaginationMode() if a pagination mode is set for any non-root elements. If these
     // styles are specified on a root element, then they will be incorporated in
     // StyleResolver::styleForDocument().
-    if ((style->overflowY() == OPAGEDX || style->overflowY() == OPAGEDY) && !(e && (e->hasTagName(htmlTag) || e->hasTagName(bodyTag))))
+    if ((style->overflowY() == OPAGEDX || style->overflowY() == OPAGEDY) && !(e && (isHTMLHtmlElement(e) || e->hasTagName(bodyTag))))
         setStylesForPaginationMode(WebCore::paginationModeForRenderStyle(style), style);
 
     // Table rows, sections and the table itself will support overflow:hidden and will ignore scroll/auto.