Bug 1290214 - Remove NS_ERROR for media queries and @font-face. r=emilio

dom/base/nsDocument.cpp

@@ -13351,7 +13351,8 @@ nsIDocument::FlushUserFontSet()
             return;
           }
         } else {
-          NS_ERROR("stylo: ServoStyleSets cannot handle @font-face rules yet");
+          NS_WARNING("stylo: ServoStyleSets cannot handle @font-face rules yet. "
+                     "See bug 1290237.");
         }
       }
 

layout/base/nsPresContext.cpp

@@ -1867,8 +1867,8 @@ nsPresContext::MediaFeatureValuesChanged(nsRestyleHint aRestyleHint,
         aRestyleHint |= eRestyle_Subtree;
       }
     } else {
-      NS_ERROR("stylo: ServoStyleSets don't support responding to medium "
-               "changes yet");
+      NS_WARNING("stylo: ServoStyleSets don't support responding to medium "
+                 "changes yet. See bug 1290228.");
     }
   }