Update our attr cache if our styles change. Bug 311557, r+sr=roc

layout/xul/base/src/nsBoxFrame.cpp

@@ -201,6 +201,14 @@ nsBoxFrame::SetInitialChildList(nsIAtom*        aListName,
   return r;
 }
 
+NS_IMETHODIMP
+nsBoxFrame::DidSetStyleContext()
+{
+  // The values that CacheAttributes() computes depend on our style,
+  // so we need to recompute them here...
+  CacheAttributes();
+}
+
 /**
  * Initialize us. This is a good time to get the alignment of the box
  */

layout/xul/base/src/nsBoxFrame.h

@@ -153,6 +153,8 @@ public:
   NS_IMETHOD  SetInitialChildList(nsIAtom*        aListName,
                                   nsIFrame*       aChildList);
 
+  NS_IMETHOD DidSetStyleContext();
+
   virtual nsIAtom* GetType() const;
 #ifdef DEBUG
   NS_IMETHOD GetFrameName(nsAString& aResult) const;