Bug 1126140 - Remove duplicated selector lists in StyleRule::List output. r=dbaron

layout/style/StyleRule.cpp

@@ -1480,14 +1480,15 @@ StyleRule::List(FILE* out, int32_t aIndent) const
     str.AppendLiteral("  ");
   }
 
-  nsAutoString buffer;
   if (mSelector) {
+    nsAutoString buffer;
     mSelector->ToString(buffer, GetStyleSheet());
     AppendUTF16toUTF8(buffer, str);
     str.Append(' ');
   }
 
   if (nullptr != mDeclaration) {
+    nsAutoString buffer;
     str.AppendLiteral("{ ");
     mDeclaration->ToString(buffer);
     AppendUTF16toUTF8(buffer, str);