Default value constants are created only call uses them

tests/compiler/dart2js/kernel/compile_from_dill_test_helper.dart

Index: tests/compiler/dart2js/kernel/compile_from_dill_test_helper.dart
diff --git a/tests/compiler/dart2js/kernel/compile_from_dill_test_helper.dart b/tests/compiler/dart2js/kernel/compile_from_dill_test_helper.dart
index eab5618d5a4c0da981234b3bda32eaf5dbd590f9..6ee336dc57b8fbe668c07a533ce374d1f88157ad 100644
--- a/tests/compiler/dart2js/kernel/compile_from_dill_test_helper.dart
+++ b/tests/compiler/dart2js/kernel/compile_from_dill_test_helper.dart
@@ -175,6 +175,18 @@ class W<Z> {}
 main() {
   print(new C<String>().a);
 }
+'''
+  }, expectIdenticalOutput: true),
+  const Test(const {
+    'main.dart': '''
+class _Marker { const _Marker(); }
+const _MARKER = const _Marker();
+class Thing<X> {
+  Thing([length = _MARKER]);
+}
+main() {
+  print(new Thing<String>(100));
+}
 '''
   }, expectIdenticalOutput: true),
 ];
@@ -192,11 +204,15 @@ Future runTests(List<String> args,
     bool skipErrors: false,
     List<String> options: const <String>[]}) async {
   Arguments arguments = new Arguments.from(args);
-  List<Test> tests;
-  if (arguments.uri != null) {
+  List<Test> tests = TESTS;
+  if (arguments.start != null) {
+    int start = arguments.start;
+    int end = arguments.end ?? 0; // Default 'end' to single test.
+    if (end > tests.length) end = tests.length; // Large 'end' means all.
+    if (end <= start) end = start + 1; // Always at least one test (else Error).
+    tests = tests.sublist(start, end);
+  } else if (arguments.uri != null) {
     tests = <Test>[new Test.fromUri(arguments.uri)];
-  } else {
-    tests = TESTS;
   }
   for (Test test in tests) {
     if (test.uri != null) {