Serialize maps without hashes.

tests/isolate/message3_test.dart

Index: tests/isolate/message3_test.dart
diff --git a/tests/isolate/message3_test.dart b/tests/isolate/message3_test.dart
index a29c8f94a931772a040b62313c68ff09c5504ecc..c07a7e68329820d9aa0e660c28e3fb5c4d808b17 100644
--- a/tests/isolate/message3_test.dart
+++ b/tests/isolate/message3_test.dart
@@ -211,6 +211,8 @@ void runTests(SendPort ping, Queue checks) {
     Expect.isTrue(x is LinkedHashMap);
     Expect.listEquals(["foo", "bar"], x.keys.toList());
     Expect.listEquals([499, 32], x.values.toList());
+    Expect.equals(499, x["foo"]);
+    Expect.equals(32, x["bar"]);
     // Must be mutable.
     x["foo"] = 22;
     Expect.equals(22, x["foo"]);
@@ -219,6 +221,28 @@ void runTests(SendPort ping, Queue checks) {
     Expect.equals(499, x["gee"]);
   });
 
+  Map<String, int> mapWithRemovedKey = {"foo": 499, "bar": 32};
+  mapWithRemovedKey.remove("foo");
+  ping.send(mapWithRemovedKey);
+  checks.add((x) {
+    Expect.isTrue(x is LinkedHashMap);
+    Expect.listEquals(["bar"], x.keys.toList());
+    Expect.listEquals([32], x.values.toList());
+    Expect.equals(32, x["bar"]);
+  });
+
+  // Test map where a key does not define ==/hashCode.
+  Map<A, int> mapWithIdentityKey = new Map<A, int>();
+  mapWithIdentityKey[new A()] = 499;
+  ping.send(mapWithIdentityKey);
+  checks.add((x) {
+    Expect.isTrue(x is LinkedHashMap);
+    int value = x.values.first;
+    Expect.equals(499, value);
+    A key = x.keys.first;
+    Expect.equals(499, x[key]);
+  });
+
   ping.send({0: 499, 1: 32});
   checks.add((x) {
     Expect.isTrue(x is LinkedHashMap);