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

sdk/lib/_internal/pub_generated/lib/src/global_packages.dart

Index: sdk/lib/_internal/pub_generated/lib/src/global_packages.dart
diff --git a/sdk/lib/_internal/pub_generated/lib/src/global_packages.dart b/sdk/lib/_internal/pub_generated/lib/src/global_packages.dart
index c12223477647e80e53952c7a463e70d7dadca838..85a1983f66e66f026736507a0325d3125e37b403 100644
--- a/sdk/lib/_internal/pub_generated/lib/src/global_packages.dart
+++ b/sdk/lib/_internal/pub_generated/lib/src/global_packages.dart
@@ -298,15 +298,18 @@ class GlobalPackages {
     });
   }
   Future<int> runExecutable(String package, String executable,
-      Iterable<String> args) {
+      Iterable<String> args, {BarbackMode mode}) {
+    if (mode == null) mode = BarbackMode.RELEASE;
     var binDir = p.join(_directory, package, 'bin');
-    if (!fileExists(p.join(binDir, '$executable.dart.snapshot'))) {
+    if (mode != BarbackMode.RELEASE ||
+        !fileExists(p.join(binDir, '$executable.dart.snapshot'))) {
       return find(package).then((entrypoint) {
         return exe.runExecutable(
             entrypoint,
             package,
             executable,
             args,
+            mode: mode,
             isGlobal: true);
       });
     }