Make binstubs run snapshots directly when possible.

sdk/lib/_internal/pub/test/global/binstubs/creates_executables_in_pubspec_test.dart

Index: sdk/lib/_internal/pub/test/global/binstubs/creates_executables_in_pubspec_test.dart
diff --git a/sdk/lib/_internal/pub/test/global/binstubs/creates_executables_in_pubspec_test.dart b/sdk/lib/_internal/pub/test/global/binstubs/creates_executables_in_pubspec_test.dart
index 616ce006142df2f22bc9f5592030da138ae9d5ec..71ae530c4c7317e5f9105bca31429623b04a04bd 100644
--- a/sdk/lib/_internal/pub/test/global/binstubs/creates_executables_in_pubspec_test.dart
+++ b/sdk/lib/_internal/pub/test/global/binstubs/creates_executables_in_pubspec_test.dart
@@ -14,12 +14,12 @@ main() {
       builder.serve("foo", "1.0.0", pubspec: {
         "executables": {
           "one": null,
-          "two-renamed": "two"
+          "two-renamed": "second"
         }
       }, contents: [
         d.dir("bin", [
           d.file("one.dart", "main(args) => print('one');"),
-          d.file("two.dart", "main(args) => print('two');"),
+          d.file("second.dart", "main(args) => print('two');"),
           d.file("nope.dart", "main(args) => print('nope');")
         ])
       ]);
@@ -30,8 +30,8 @@ main() {
 
     d.dir(cachePath, [
       d.dir("bin", [
-        d.matcherFile("one", contains("pub global run foo:one")),
-        d.matcherFile("two-renamed", contains("pub global run foo:two")),
+        d.matcherFile("one", contains("one")),
+        d.matcherFile("two-renamed", contains("second")),
         d.nothing("two"),
         d.nothing("nope")
       ])