Make sure isolate library is initialized before using isolate natives.

The compiler only adds 'startRootIsolate' if we use the dart:isolate library.

===
    if (hasIsolateSupport()) {
      enqueuer.codegen.addToWorkList(
          isolateHelperLibrary.find(Compiler.START_ROOT_ISOLATE));
      enqueuer.codegen.registerGetOfStaticFunction(main);
    }
===

However the isolate-native library requires some of the startRootIsolate
elements to be resolved. Therefore we must use the dart:isolate library
in the native-isolate tests.

Review URL: https://codereview.chromium.org//167493002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@32709 260f80e4-7a28-3924-810f-c04153c831b5

sdk/lib/_internal/lib/isolate_helper.dart

@@ -501,6 +501,8 @@ typedef _MainFunction();
 typedef _MainFunctionArgs(args);
 typedef _MainFunctionArgsMessage(args, message);
 
+/// Note: IsolateNatives depends on _globalState which is only set up correctly
+/// when 'dart:isolate' has been imported.
 class IsolateNatives {
 
   static String thisScript = computeThisScript();

tests/compiler/dart2js_native/compute_this_script_test.dart

@@ -5,8 +5,14 @@
 // Test of IsolateNatives.computeThisScript().
 
 import 'dart:_isolate_helper';
+// The isolate helper library is not correctly set up if the dart:isolate
+// library hasn't been loaded.
+import 'dart:isolate';
 
 main() {
+  // Need to use the isolate-library so dart2js correctly initializes the
+  // library.
+  Capability cab = new Capability();
   String script = IsolateNatives.computeThisScript();
 
   // This is somewhat brittle and relies on an implementation detail

tests/compiler/dart2js_native/dart2js_native.status

@@ -22,6 +22,3 @@ only_pass_on_d8_test: Fail, OK # This test should only pass on D8.
 
 [ $browser || $runtime == d8 ]
 only_pass_on_jsshell_test: Fail, OK # This test should only pass on jsshell.
-
-[ $compiler == dart2js && $checked && $runtime == d8 ]
-compute_this_script_test: Crash # TODO(floitsch): Mark as failing while debugging.