Add an Environment class that's exposed through RunnerSuite.

lib/src/runner/runner_suite.dart

Index: lib/src/runner/runner_suite.dart
diff --git a/lib/src/runner/runner_suite.dart b/lib/src/runner/runner_suite.dart
index 10064afe244a84c8fcda7b4e9f23c07c8307297a..2407f69fd267702c984fed1a95b159aa24fb7acc 100644
--- a/lib/src/runner/runner_suite.dart
+++ b/lib/src/runner/runner_suite.dart
@@ -14,6 +14,7 @@ import '../backend/suite.dart';
 import '../backend/test.dart';
 import '../backend/test_platform.dart';
 import '../utils.dart';
+import 'environment.dart';
 
 /// A suite produced and consumed by the test runner that has runner-specific
 /// logic and lifecycle management.
@@ -22,33 +23,27 @@ import '../utils.dart';
 /// eventually become its own package) is primarily for test code itself to use,
 /// for which the [RunnerSuite] APIs don't make sense.
 class RunnerSuite extends Suite {
+  final Environment environment;
+
   /// The memoizer for running [close] exactly once.
   final _closeMemo = new AsyncMemoizer();
 
   /// The function to call when the suite is closed.
   final AsyncFunction _onClose;
 
-  RunnerSuite(Iterable<Test> tests, {String path, TestPlatform platform,
-          OperatingSystem os, Metadata metadata, AsyncFunction onClose})
+  RunnerSuite(this.environment, Iterable<Test> tests, {String path,
+          TestPlatform platform, OperatingSystem os, Metadata metadata,
+          AsyncFunction onClose})
       : super(tests,
           path: path, platform: platform, os: os, metadata: metadata),
         _onClose = onClose;
 
-  /// Creates a new [RunnerSuite] with the same properties as [suite].
-  RunnerSuite.fromSuite(Suite suite)
-      : super(suite.tests,
-          path: suite.path,
-          platform: suite.platform,
-          os: suite.os,
-          metadata: suite.metadata),
-        _onClose = null;
-
   RunnerSuite change({String path, Metadata metadata, Iterable<Test> tests}) {
     if (path == null) path = this.path;
     if (metadata == null) metadata = this.metadata;
     if (tests == null) tests = this.tests;
-    return new RunnerSuite(tests, platform: platform, os: os, path: path,
-        metadata: metadata, onClose: this.close);
+    return new RunnerSuite(environment, tests, platform: platform, os: os,
+        path: path, metadata: metadata, onClose: close);
   }
 
   /// Closes the suite and releases any resources associated with it.