Add a --mode flag to pub run and pub global run.

sdk/lib/_internal/pub/lib/src/command/run.dart

Index: sdk/lib/_internal/pub/lib/src/command/run.dart
diff --git a/sdk/lib/_internal/pub/lib/src/command/run.dart b/sdk/lib/_internal/pub/lib/src/command/run.dart
index 1e3a50130df58cca874c7b830602c08179bcbde2..42a0d370625ba6dac1ccb4aa2e7d7bd2ad54655b 100644
--- a/sdk/lib/_internal/pub/lib/src/command/run.dart
+++ b/sdk/lib/_internal/pub/lib/src/command/run.dart
@@ -6,6 +6,7 @@ library pub.command.run;
 
 import 'dart:async';
 
+import 'package:barback/barback.dart';
 import 'package:path/path.dart' as p;
 
 import '../command.dart';
@@ -21,6 +22,13 @@ class RunCommand extends PubCommand {
       "NOTE: We are currently optimizing this command's startup time.";
   String get usage => "pub run <executable> [args...]";
 
+  RunCommand() {
+    commandParser.addOption("mode",
+        help: 'Mode to run transformers in.\n'
+              '(defaults to "release" for dependencies, "debug" for '
+                'entrypoint)');
+  }
+
   Future onRun() async {
     if (commandOptions.rest.isEmpty) {
       usageError("Must specify an executable to run.");
@@ -45,7 +53,17 @@ class RunCommand extends PubCommand {
       }
     }
 
-    var exitCode = await runExecutable(entrypoint, package, executable, args);
+    var mode;
+    if (commandOptions['mode'] != null) {
+      mode = new BarbackMode(commandOptions['mode']);
+    } else if (package == entrypoint.root.name) {
+      mode = BarbackMode.DEBUG;
+    } else {
+      mode = BarbackMode.RELEASE;
+    }
+
+    var exitCode = await runExecutable(entrypoint, package, executable, args,
+        mode: mode);
     await flushThenExit(exitCode);
   }
 }