Very simple version of Isolates.

tests/lib/lib.status

Index: tests/lib/lib.status
diff --git a/tests/lib/lib.status b/tests/lib/lib.status
index 01cbc412581b59dca642ea088d55edffef29b226..9c640560b5b24a64fba34b206f5312a3acaeb2da 100644
--- a/tests/lib/lib.status
+++ b/tests/lib/lib.status
@@ -7,7 +7,6 @@ mirrors/delegate_test: RuntimeError # Issue 13864
 
 [ $compiler == dart2js ]
 async/schedule_microtask3_test: RuntimeError # _enqueueImmediate runs after Timer. http://dartbug.com/9002
-async/schedule_microtask4_test: Pass, RuntimeError # no global exception handler in isolates. http://dartbug.com/9012
 async/schedule_microtask6_test: RuntimeError # global error handling is not supported. http://dartbug.com/5958
 
 math/double_pow_test: RuntimeError
@@ -178,7 +177,6 @@ mirrors/typedef_test/01: Fail, OK # Incorrect dart2js behavior.
 mirrors/generic_f_bounded_test/01: RuntimeError # Issue 14000
 mirrors/symbol_validation_test: RuntimeError # Issue 13596
 
-async/timer_isolate_test: Skip # See Issue 4997
 async/timer_not_available_test: SkipByDesign # only meant to test when there is no way to implement timer (currently only in d8)
 
 [ $compiler == none && ( $runtime == drt || $runtime == dartium ) ]
@@ -186,7 +184,6 @@ mirrors/immutable_collections_test: Fail # Issue 11857, Issue 14321
 mirrors/library_uri_io_test: Skip # Not intended for drt as it uses dart:io.
 mirrors/local_isolate_test: Skip # http://dartbug.com/12188
 async/schedule_microtask6_test: Fail # Issue 10910
-async/schedule_microtask4_test: Fail # Issue 13921
 platform/isolate_test: Skip # Issue 14444
 
 [ $compiler == none && $runtime == drt && $mode == debug ]