Bug 1153484 - Fetch should ignore invalid headers, but still process later headers. r=nsm

dom/fetch/FetchDriver.cpp

@@ -20,6 +20,7 @@
 #include "nsDataHandler.h"
 #include "nsHostObjectProtocolHandler.h"
 #include "nsNetUtil.h"
+#include "nsPrintfCString.h"
 #include "nsStreamUtils.h"
 #include "nsStringStream.h"
 
@@ -629,7 +630,13 @@ public:
   {
     ErrorResult result;
     mResponse->Headers()->Append(aHeader, aValue, result);
-    return result.ErrorCode();
+    if (result.Failed()) {
+      NS_WARNING(nsPrintfCString("Fetch ignoring illegal header - '%s': '%s'",
+                                 PromiseFlatCString(aHeader).get(),
+                                 PromiseFlatCString(aValue).get()).get());
+      result.ClearMessage();
+    }
+    return NS_OK;
   }
 };