Add support for native ports in the vm.

runtime/vm/allocation.cc

 // 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.
 
 #include "vm/allocation.h"
 
 #include "platform/assert.h"
 #include "vm/isolate.h"
 #include "vm/zone.h"
 
 namespace dart {
 
-StackResource::StackResource(Isolate* isolate) : isolate_(isolate) {
-  previous_ = isolate->top_resource();
-  isolate->set_top_resource(this);
+StackResource::StackResource(Isolate* isolate)
+    : isolate_(isolate), previous_(NULL) {
+  // We can only have longjumps and exceptions when there is a current
+  // isolate.  If there is no current isolate, we don't need to
+  // protect this case.
+  if (isolate) {
+    previous_ = isolate->top_resource();
+    isolate->set_top_resource(this);
+  }
 }
 
 
 StackResource::~StackResource() {
-  StackResource* top = isolate()->top_resource();
-  ASSERT(top == this);
-  isolate()->set_top_resource(previous_);
+  if (isolate()) {
+    StackResource* top = isolate()->top_resource();
+    ASSERT(top == this);
+    isolate()->set_top_resource(previous_);
+  }
+  ASSERT(Isolate::Current() == isolate());
 }
 
 ZoneAllocated::~ZoneAllocated() {
   UNREACHABLE();
 }
 
 void* ZoneAllocated::operator new(uword size) {
   Isolate* isolate = Isolate::Current();
   ASSERT(isolate != NULL);
   ASSERT(isolate->current_zone() != NULL);
   return reinterpret_cast<void*>(isolate->current_zone()->Allocate(size));
 }
 
 }  // namespace dart