Remove fake isolate from concurrent sweeper and extend lifetime of VM threads.

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
===================================================================
--- runtime/vm/isolate.cc	(revision 45808)
+++ runtime/vm/isolate.cc	(working copy)
@@ -620,71 +620,6 @@
   set_user_tag(UserTags::kDefaultUserTag);
 }
 
-Isolate::Isolate(Isolate* original)
-  :   mutator_thread_(NULL),
-      vm_tag_(0),
-      store_buffer_(true),
-      class_table_(original->class_table()),
-      message_notify_callback_(NULL),
-      name_(NULL),
-      debugger_name_(NULL),
-      start_time_(OS::GetCurrentTimeMicros()),
-      main_port_(0),
-      pause_capability_(0),
-      terminate_capability_(0),
-      errors_fatal_(true),
-      heap_(NULL),
-      object_store_(NULL),
-      top_exit_frame_info_(0),
-      init_callback_data_(NULL),
-      environment_callback_(NULL),
-      library_tag_handler_(NULL),
-      api_state_(NULL),
-      stub_code_(NULL),
-      debugger_(NULL),
-      single_step_(false),
-      resume_request_(false),
-      random_(),
-      simulator_(NULL),
-      long_jump_base_(NULL),
-      timer_list_(),
-      deopt_id_(0),
-      mutex_(new Mutex()),
-      stack_limit_(0),
-      saved_stack_limit_(0),
-      stack_overflow_flags_(0),
-      stack_overflow_count_(0),
-      message_handler_(NULL),
-      spawn_state_(NULL),
-      is_runnable_(false),
-      gc_prologue_callback_(NULL),
-      gc_epilogue_callback_(NULL),
-      defer_finalization_count_(0),
-      deopt_context_(NULL),
-      edge_counter_increment_size_(-1),
-      compiler_stats_(NULL),
-      is_service_isolate_(false),
-      log_(new class Log()),
-      stacktrace_(NULL),
-      stack_frame_index_(-1),
-      last_allocationprofile_accumulator_reset_timestamp_(0),
-      last_allocationprofile_gc_timestamp_(0),
-      object_id_ring_(NULL),
-      trace_buffer_(NULL),
-      profiler_data_(NULL),
-      thread_state_(NULL),
-      tag_table_(GrowableObjectArray::null()),
-      current_tag_(UserTag::null()),
-      default_tag_(UserTag::null()),
-      deoptimized_code_array_(GrowableObjectArray::null()),
-      metrics_list_head_(NULL),
-      cha_(NULL),
-      next_(NULL),
-      pause_loop_monitor_(NULL),
-      REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_INITIALIZERS)
-      REUSABLE_HANDLE_LIST(REUSABLE_HANDLE_SCOPE_INIT)
-      reusable_handles_() {
-}
 #undef REUSABLE_HANDLE_SCOPE_INIT
 #undef REUSABLE_HANDLE_INITIALIZERS
 
@@ -1464,11 +1399,6 @@
 }
 
 
-Isolate* Isolate::ShallowCopy() {
-  return new Isolate(this);
-}
-
-
 Dart_IsolateCreateCallback Isolate::create_callback_ = NULL;
 Dart_IsolateInterruptCallback Isolate::interrupt_callback_ = NULL;
 Dart_IsolateUnhandledExceptionCallback