Support directories other than "web" in pub build.

sdk/lib/_internal/pub/bin/pub.dart

Index: sdk/lib/_internal/pub/bin/pub.dart
diff --git a/sdk/lib/_internal/pub/bin/pub.dart b/sdk/lib/_internal/pub/bin/pub.dart
index 777105ba1b0fcea6e3e1e1ed97345b8a184413d1..a589dcc8403a9ac31593a593ad2afb4545c1f627 100644
--- a/sdk/lib/_internal/pub/bin/pub.dart
+++ b/sdk/lib/_internal/pub/bin/pub.dart
@@ -19,7 +19,8 @@ void main(List<String> arguments) {
   ArgResults options;
 
   try {
-    options = PubCommand.pubArgParser.parse(arguments);
+    options = PubCommand.pubArgParser.parse(arguments,
+        allowTrailingOptions: true);
   } on FormatException catch (e) {
     log.error(e.message);
     log.error('Run "pub help" to see available options.');