Remove import of collection-dev.

pkg/serialization/lib/src/format.dart

Index: pkg/serialization/lib/src/format.dart
diff --git a/pkg/serialization/lib/src/format.dart b/pkg/serialization/lib/src/format.dart
index 9b6805cd4487065b0f413bf4e8f8f1c96c98cd2d..6e40e0ad797ce3c129b79e8c6b1636f04e4edbf9 100644
--- a/pkg/serialization/lib/src/format.dart
+++ b/pkg/serialization/lib/src/format.dart
@@ -184,12 +184,7 @@ class SimpleJsonFormat extends Format {
     } else {
       throw new SerializationException("Invalid data format");
     }
-    var newData = values(data).mappedBy(
-        (x) => recursivelyFixUp(x, r, result));
-    // TODO(alanknight): Ugh. Get rid of this if we can resolve bug 7982/7940.
-    if (newData is MappedList) {
-      newData = newData.toList();
-    }
+    var newData = mapValues(data, (x) => recursivelyFixUp(x, r, result));
     result[ruleNumber].add(newData);
     return new Reference(r, ruleNumber, result[ruleNumber].length - 1);
   }