Support running executables from dependencies.

sdk/lib/_internal/pub/test/run/nonexistent_script_in_dependency_test.dart

Index: sdk/lib/_internal/pub/test/run/nonexistent_script_in_dependency_test.dart
diff --git a/sdk/lib/_internal/pub/test/run/nonexistent_script_test.dart b/sdk/lib/_internal/pub/test/run/nonexistent_script_in_dependency_test.dart
similarity index 57%
copy from sdk/lib/_internal/pub/test/run/nonexistent_script_test.dart
copy to sdk/lib/_internal/pub/test/run/nonexistent_script_in_dependency_test.dart
index cb233b38b4530ea6eea8260ebc8f1ecf1cfcf9c7..5919b7e042cc527b4e0265204d9a4a242fdffeb5 100644
--- a/sdk/lib/_internal/pub/test/run/nonexistent_script_test.dart
+++ b/sdk/lib/_internal/pub/test/run/nonexistent_script_in_dependency_test.dart
@@ -9,13 +9,21 @@ import 'utils.dart';
 
 main() {
   initConfig();
-  integration('Errors if the script does not exist.', () {
+  integration('Errors if the script in a dependency does not exist.', () {
+    d.dir("foo", [
+      d.libPubspec("foo", "1.0.0")
+    ]).create();
+
     d.dir(appPath, [
-      d.appPubspec()
+      d.appPubspec({
+        "foo": {"path": "../foo"}
+      })
     ]).create();
 
-    var pub = pubRun(args: ["script"]);
-    pub.stderr.expect("Could not find bin/script.dart.");
+    pubGet();
+
+    var pub = pubRun(args: ["foo:script"]);
+    pub.stderr.expect("Could not find bin/script.dart in package foo.");
     pub.shouldExit(exit_codes.NO_INPUT);
   });
 }