Make dart:developer log more user friendly

runtime/lib/developer.dart

Index: runtime/lib/developer.dart
diff --git a/runtime/lib/developer.dart b/runtime/lib/developer.dart
index 242ef04603056d75b3e790633d60029161555881..e14e4f9d537ea1bf13781b18f2b3e4b03b277b60 100644
--- a/runtime/lib/developer.dart
+++ b/runtime/lib/developer.dart
@@ -6,11 +6,42 @@ patch bool debugger({bool when: true, String msg}) native "Developer_debugger";
 
 patch inspect(object) native "Developer_inspect";
 
-patch log({int sequenceNumber,
-           int millisecondsSinceEpoch,
+patch log(String message,
+          DateTime time,
+          {int sequenceNumber,
            int level,

[Lasse Reichstein Nielsen, 2015/08/04 11:24:54]

Add default value for level and name.

[Cutch, 2015/08/04 14:11:40]

Done.

            String name,
-           String message,
            Zone zone,
            Object error,
-           StackTrace stackTrace}) native "Developer_log";
+           StackTrace stackTrace}) {
+  if (message is! String) {
+    throw new ArgumentError("message must be an instance of String");

[Lasse Reichstein Nielsen, 2015/08/04 11:24:54]

throw new ArgumentError.value(message, "message", "Must be a String");

[Cutch, 2015/08/04 14:11:40]

Done.

+  }
+  if (time is! DateTime) {
+    throw new ArgumentError("time must be an instance of DateTime");

[Lasse Reichstein Nielsen, 2015/08/04 11:24:54]

throw new ArgumentError.value(time, "time", "Must be a DateTime");

[Cutch, 2015/08/04 14:11:40]

Done.

+  }
+  if (sequenceNumber == null) {
+    sequenceNumber = _lastSequenceNumber++;

[Lasse Reichstein Nielsen, 2015/08/04 11:24:54]

-> ++_lastSequenceNumber 
(otherwise you will repeat the the last specified sequence number once)
Alternatively, if you want to start at 0, rename _lastSequenceNumber to
_nextSequenceNumber and store "sequenceNumber + 1" below instead)

[Cutch, 2015/08/04 14:11:40]

Done.

+  } else {
+    _lastSequenceNumber = sequenceNumber;
+  }
+  return _log(message,
+              time.millisecondsSinceEpoch,
+              sequenceNumber,
+              level,
+              name,
+              zone,
+              error,
+              stackTrace);
+}
+
+int _lastSequenceNumber = 0;
+
+_log(String message,
+     DateTime time,
+     int sequenceNumber,
+     int level,
+     String name,
+     Zone zone,
+     Object error,
+     StackTrace stackTrace) native "Developer_log";