Bug 1614208 - Stop including nsStyleConsts.h from WebRenderTypes.h. r=jrmuizel

This is another one which is included everywhere. If the OOL call mattered we
could move these to a different header or something, but I suspect it won't.

Differential Revision: https://phabricator.services.mozilla.com/D62173

toolkit/components/browser/nsWebBrowser.cpp

@@ -37,6 +37,7 @@
 
 // for painting the background window
 #include "mozilla/LookAndFeel.h"
+#include "mozilla/ServoStyleConsts.h"
 
 // Printing Includes
 #ifdef NS_PRINTING