Fix rather serious build warning about passing non-POD types to printf. DEBUG-only

layout/style/nsCSSStyleRule.cpp

@@ -879,7 +879,7 @@ CSSImportantRule::List(FILE* out, PRInt32 aIndent) const
   // Indent
   for (PRInt32 index = aIndent; --index >= 0; ) fputs("  ", out);
 
-  fprintf(out, "! Important rule block=%p\n", mImportantBlock);
+  fprintf(out, "! Important rule block=%p\n", mImportantBlock.get());
   return NS_OK;
 }
 #endif