Move things that aren't author stylesheets out of nsDocument's mStyleSheets array to simplify stylesheet management code. Add a level of the cascade for style attributes and ensure that there's only one rule processor per level of the cascade, and simplify the logic of nsCSSRuleProcessor creation. b=252578 r+sr=bzbarsky

layout/style/nsHTMLStyleSheet.cpp

@@ -499,15 +499,6 @@ nsHTMLStyleSheet::~nsHTMLStyleSheet()
 
 NS_IMPL_ISUPPORTS2(nsHTMLStyleSheet, nsIStyleSheet, nsIStyleRuleProcessor)
 
-NS_IMETHODIMP
-nsHTMLStyleSheet::GetStyleRuleProcessor(nsIStyleRuleProcessor*& aProcessor,
-                                        nsIStyleRuleProcessor* /*aPrevProcessor*/)
-{
-  aProcessor = this;
-  NS_ADDREF(aProcessor);
-  return NS_OK;
-}
-
 static nsresult GetBodyColor(nsIPresContext* aPresContext, nscolor* aColor)
 {
   nsCOMPtr<nsIDocument> doc;