Better checking and error reporting for HTTP client

runtime/bin/http_impl.dart

Index: runtime/bin/http_impl.dart
diff --git a/runtime/bin/http_impl.dart b/runtime/bin/http_impl.dart
index 836a9439d908bf48431a1a58f538cc309e581166..96d4373b2f8b994a8aae25c00bdf45f5c22ffaec 100644
--- a/runtime/bin/http_impl.dart
+++ b/runtime/bin/http_impl.dart
@@ -1262,6 +1262,8 @@ class _HttpClientConnection
     if (e != null) {
       if (_onErrorCallback != null) {
         _onErrorCallback(e);
+      } else {
+        throw e;
       }
     }
     _closing = true;
@@ -1366,6 +1368,9 @@ class _HttpClient implements HttpClient {
   HttpClientConnection open(
       String method, String host, int port, String path) {
     if (_shutdown) throw new HttpException("HttpClient shutdown");
+    if (method == null || host == null || port == null || path == null) {
+      throw new NullPointerException();

[Mads Ager (google), 2012/05/03 13:36:28]

We could throw a more descriptive error here? Not sure it matters much so I'll
leave it up to you.

Is null the only thing we need to check here because other checks are done
later?

[Søren Gjesse, 2012/05/07 11:42:31]

Changed to IllegalArgumentException.

Arguments are type checked later.

+    }
     return _prepareHttpClientConnection(host, port, method, path);
   }