Reapply "Dart2js testing: Add prefix files when running dart2js output on d8 or jsshell.""

tools/testing/dart/runtime_configuration.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 library runtime_configuration;
 
 import 'compiler_configuration.dart' show
     CommandArtifact;
 
 // TODO(ahe): Remove this import, we can precompute all the values required
@@ skipping 58 matching lines @@
 
   List<Command> computeRuntimeCommands(
       TestSuite suite,
       CommandBuilder commandBuilder,
       CommandArtifact artifact,
       List<String> arguments,
       Map<String, String> environmentOverrides) {
     // TODO(ahe): Make this method abstract.
     throw "Unimplemented runtime '$runtimeType'";
   }
+
+  List<String> dart2jsPreambles(Uri preambleDir) => [];
 }
 
 /// The 'none' runtime configuration.
 class NoneRuntimeConfiguration extends RuntimeConfiguration {
   NoneRuntimeConfiguration()
       : super._subclass();
 
   List<Command> computeRuntimeCommands(
       TestSuite suite,
       CommandBuilder commandBuilder,
@@ skipping 28 matching lines @@
       CommandBuilder commandBuilder,
       CommandArtifact artifact,
       List<String> arguments,
       Map<String, String> environmentOverrides) {
     // TODO(ahe): Avoid duplication of this method between d8 and jsshell.
     checkArtifact(artifact);
     return <Command>[
         commandBuilder.getJSCommandlineCommand(
             moniker, suite.d8FileName, arguments, environmentOverrides)];
   }
+
+  List<String> dart2jsPreambles(Uri preambleDir) {
+    return [preambleDir.resolve('d8.js').toFilePath()];
+  }
 }
 
 /// Firefox/SpiderMonkey-based development shell (jsshell).
 class JsshellRuntimeConfiguration extends CommandLineJavaScriptRuntime {
   JsshellRuntimeConfiguration()
       : super('jsshell');
 
   List<Command> computeRuntimeCommands(
       TestSuite suite,
       CommandBuilder commandBuilder,
       CommandArtifact artifact,
       List<String> arguments,
       Map<String, String> environmentOverrides) {
     checkArtifact(artifact);
     return <Command>[
         commandBuilder.getJSCommandlineCommand(
             moniker, suite.jsShellFileName, arguments, environmentOverrides)];
   }
+
+  List<String> dart2jsPreambles(Uri preambleDir) {
+    return ['-f', preambleDir.resolve('jsshell.js').toFilePath(), '-f'];
+  }
 }
 
 /// Common runtime configuration for runtimes based on the Dart VM.
 class DartVmRuntimeConfiguration extends RuntimeConfiguration {
   DartVmRuntimeConfiguration()
       : super._subclass();
 
   int computeTimeoutMultiplier({
       bool isDebug: false,
       bool isChecked: false,
@@ skipping 54 matching lines @@
 class DummyRuntimeConfiguration extends DartVmRuntimeConfiguration {
   List<Command> computeRuntimeCommands(
       TestSuite suite,
       CommandBuilder commandBuilder,
       CommandArtifact artifact,
       List<String> arguments,
       Map<String, String> environmentOverrides) {
     throw "Unimplemented runtime '$runtimeType'";
   }
 }