Stop using cURL in Pub.

utils/pub/http.dart

Index: utils/pub/http.dart
diff --git a/utils/pub/http.dart b/utils/pub/http.dart
index e148418e686501496dd26f2617b344ce090370cc..f8cb6994b70f66e033867ccfe3cb8165af06172e 100644
--- a/utils/pub/http.dart
+++ b/utils/pub/http.dart
@@ -11,7 +11,6 @@ import 'dart:json' as json;
 
 // TODO(nweiz): Make this import better.
 import '../../pkg/http/lib/http.dart' as http;
-import 'curl_client.dart';
 import 'io.dart';
 import 'log.dart' as log;
 import 'utils.dart';
@@ -57,12 +56,16 @@ class PubHttpClient extends http.BaseClient {
       });
     }).catchError((asyncError) {
       if (asyncError.error is SocketIOException &&
-          asyncError.error.osError != null &&
-          (asyncError.error.osError.errorCode == 8 ||
-           asyncError.error.osError.errorCode == -2 ||
-           asyncError.error.osError.errorCode == -5 ||
-           asyncError.error.osError.errorCode == 11004)) {
-        throw 'Could not resolve URL "${request.url.origin}".';
+          asyncError.error.osError != null) {
+        if (asyncError.error.osError.errorCode == 8 ||
+            asyncError.error.osError.errorCode == -2 ||
+            asyncError.error.osError.errorCode == -5 ||
+            asyncError.error.osError.errorCode == 11004) {
+          throw 'Could not resolve URL "${request.url.origin}".';
+        } else if (asyncError.error.osError.errorCode == -12276) {
+          throw 'Unable to validate SSL certificate for '
+              '"${request.url.origin}".';
+        }
       }
       throw asyncError;
     }), HTTP_TIMEOUT, 'fetching URL "${request.url}"');
@@ -72,8 +75,6 @@ class PubHttpClient extends http.BaseClient {
 /// The HTTP client to use for all HTTP requests.
 final httpClient = new PubHttpClient();
 
-final curlClient = new PubHttpClient(new CurlClient());
-
 /// Handles a successful JSON-formatted response from pub.dartlang.org.
 ///
 /// These responses are expected to be of the form `{"success": {"message":