Add firefox jsshell support in testing scripts.

tools/testing/dart/test_suite.dart

Index: tools/testing/dart/test_suite.dart
===================================================================
--- tools/testing/dart/test_suite.dart	(revision 13217)
+++ tools/testing/dart/test_suite.dart	(working copy)
@@ -469,6 +469,10 @@
       } else if (configuration['runtime'] == 'd8') {
         var d8 = TestUtils.d8FileName(configuration);
         commands.add(new Command(d8, ['$tempDir/out.js']));
+      } else if (configuration['runtime'] == 'jsshell') {
+        var jsshell = TestUtils.jsshellFileName(configuration);
+        var environment = TestUtils.jsshellEnvironment(configuration);
+        commands.add(new Command(jsshell, ['$tempDir/out.js'], environment));
       }
       return commands;
 
@@ -1267,7 +1271,10 @@
 
   static String executableSuffix(String executable) {
     if (Platform.operatingSystem == 'windows') {
-      if (executable == 'd8' || executable == 'vm' || executable == 'none') {
+      if (executable == 'd8' ||
+          executable == 'vm' ||
+          executable == 'none'  ||
+          executable == 'jsshell') {
         return '.exe';
       } else {
         return '.bat';
@@ -1398,6 +1405,26 @@
     return args;
   }
 
+  static String jsshellDir(Map configuration) {
+    var base = dartDir();
+    return '$base/third_party/firefox_jsshell/${configuration['system']}';
+  }
+
+  static String jsshellFileName(Map configuration) {
+    var executableSuffix = executableSuffix('jsshell');
+    var executable = 'js$executableSuffix';
+    var jsshellDir = jsshellDir(configuration);
+    return '$jsshellDir/$executable';
+  }
+
+  static Map<String, String> jsshellEnvironment(Map configuration) {
+    if (configuration['system'] == 'linux') {
+      var jsshellDir = jsshellDir(configuration);
+      return {'LD_LIBRARY_PATH': jsshellDir};
+    }
+    return {};
+  }
+
   static bool isBrowserRuntime(String runtime) => Contains(
       runtime,
       const <String>['drt',
@@ -1407,6 +1434,10 @@
                      'opera',
                      'chrome',
                      'ff']);
+
+  static bool isJsCommandLineRuntime(String runtime) =>
+      Contains(runtime, const <String>['d8', 'jsshell']);
+
 }
 
 class SummaryReport {