Support PhantomJS.

lib/src/backend/test_platform.dart

Index: lib/src/backend/test_platform.dart
diff --git a/lib/src/backend/test_platform.dart b/lib/src/backend/test_platform.dart
index 881dcf4aa27e52b176181671947f259e9799faa7..f2577d486f7b30921bbecd85cc6141e5859ca369 100644
--- a/lib/src/backend/test_platform.dart
+++ b/lib/src/backend/test_platform.dart
@@ -27,13 +27,18 @@ class TestPlatform {
   static const TestPlatform chrome = const TestPlatform._("Chrome", "chrome",
       isBrowser: true, isJS: true, isBlink: true);
 
+  /// PhantomJS.
+  static const TestPlatform phantomJS = const TestPlatform._(
+      "PhantomJS", "phantomjs",
+      isBrowser: true, isJS: true, isBlink: true);
+
   /// Mozilla Firefox.
   static const TestPlatform firefox = const TestPlatform._("Firefox", "firefox",
       isBrowser: true, isJS: true);
 
   /// A list of all instances of [TestPlatform].
   static const List<TestPlatform> all =
-      const [vm, dartium, contentShell, chrome, firefox];
+      const [vm, dartium, contentShell, chrome, phantomJS, firefox];
 
   /// Finds a platform by its identifier string.
   ///