Add ./tools/test.py -c precompiler -r dart_precompiled.

tools/testing/dart/test_runner.dart

Index: tools/testing/dart/test_runner.dart
diff --git a/tools/testing/dart/test_runner.dart b/tools/testing/dart/test_runner.dart
index 97ad17ac578ba7e8539a8034bd6c26fbca429ae8..6010540d75aaf09cf485a95c2ee9dfb71cd4a42a 100644
--- a/tools/testing/dart/test_runner.dart
+++ b/tools/testing/dart/test_runner.dart
@@ -1679,6 +1679,10 @@ CommandOutput createCommandOutput(Command command,
     return new VmCommandOutputImpl(
         command, exitCode, timedOut, stdout, stderr, time, pid);
   } else if (command is CompilationCommand) {
+    if (command.displayName == 'precompiler.dart') {
+      return new VmCommandOutputImpl(
+          command, exitCode, timedOut, stdout, stderr, time, pid);
+    }
     return new CompilationCommandOutputImpl(
         command, exitCode, timedOut, stdout, stderr, time, compilationSkipped);
   } else if (command is JSCommandlineCommand) {