Revert 190605 "Make RenderObject::style() return a const object"

trunk/Source/core/dom/Document.h

Index: trunk/Source/core/dom/Document.h
===================================================================
--- trunk/Source/core/dom/Document.h	(revision 190671)
+++ trunk/Source/core/dom/Document.h	(working copy)
@@ -789,7 +789,7 @@
     // that as the style for the root element, rather than obtaining it on our own. The reason for
     // this is that style may not have been associated with the elements yet - in which case it may
     // have been calculated on the fly (without associating it with the actual element) somewhere.
-    Element* viewportDefiningElement(const LayoutStyle* rootStyle = nullptr) const;
+    Element* viewportDefiningElement(LayoutStyle* rootStyle = nullptr) const;
 
     DocumentMarkerController& markers() const { return *m_markers; }