isolates refactor: this change introduces 'dart:isolate' as a library. This is a

frog/gen.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /**
  * Top level generator object for writing code and keeping track of
  * dependencies.
  *
  * Should have two compilation models, but only one implemented so far.
  *
@@ skipping 71 matching lines @@
     world.stringImplType.markUsed();
 
     if (corejs.useIndex || corejs.useSetIndex) {
       if (!options.disableBoundsChecks) {
         // These exceptions might be thrown by array bounds checks.
         markTypeUsed(world.corelib.types['IndexOutOfRangeException']);
         markTypeUsed(world.corelib.types['IllegalArgumentException']);
       }
     }
 
-    // Only include isolate-specific code if isolates are used.
-    if (world.corelib.types['Isolate'].isUsed
-        || world.coreimpl.types['ReceivePortImpl'].isUsed) {
-
-      // Generate callbacks from JS to isolate code if needed
-      if (corejs.useWrap0 || corejs.useWrap1) {
-        genMethod(world.coreimpl.types['IsolateContext'].getMember('eval'));
-        genMethod(world.coreimpl.types['EventLoop'].getMember('run'));
-      }
-
+    // Only wrap the app as an isolate if the isolate library was imported.
+    if (world.isolatelib != null) {
       corejs.useIsolates = true;
       MethodMember isolateMain =
-        world.coreimpl.lookup('startRootIsolate', main.span);
-      var isolateMainTarget = new TypeValue(world.coreimpl.topType, main.span);
-      mainCall = isolateMain.invoke(mainContext, null, isolateMainTarget,
+        world.isolatelib.lookup('startRootIsolate', main.span);
+      mainCall = isolateMain.invoke(mainContext, null,
+          new TypeValue(world.isolatelib.topType, main.span),
           new Arguments(null, [main._get(mainContext, main.definition, null)]));
     }
 
     writeTypes(world.coreimpl);
     writeTypes(world.corelib);
 
     // Write the main library. This will cause all libraries to be written in
     // the topological sort order.
     writeTypes(main.declaringType.library);
 
@@ skipping 2341 matching lines @@
     return true;
   }
 
 }
 
 class ReturnKind {
   static final int IGNORE = 1;
   static final int POST = 2;
   static final int PRE = 3;
 }