Make sure isolate library is initialized before using isolate natives.

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.

Committed: https://code.google.com/p/dart/source/detail?r=32709

[floitsch, 2014-02-14 19:10:26]

TBR.

[floitsch, 2014-02-14 19:10:48]

Committed patchset #1 manually as r32709 (presubmit successful).

[sigurdm, 2014-02-17 08:25:40]

lgtm