Do not chain the current context on entry in non-closure functions, but

runtime/vm/object.h

 // 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.
 
 #ifndef VM_OBJECT_H_
 #define VM_OBJECT_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/utils.h"
@@ skipping 2138 matching lines @@
 
   HEAP_OBJECT_IMPLEMENTATION(Code, Object);
   friend class Class;
 };
 
 
 class Context : public Object {
  public:
   RawContext* parent() const { return raw_ptr()->parent_; }
   void set_parent(const Context& parent) const {
-    ASSERT(parent.isolate() == Isolate::Current());
+    ASSERT(parent.IsNull() || parent.isolate() == Isolate::Current());
     StorePointer(&raw_ptr()->parent_, parent.raw());
   }
   static intptr_t parent_offset() { return OFFSET_OF(RawContext, parent_); }
 
   Isolate* isolate() const { return raw_ptr()->isolate_; }
   static intptr_t isolate_offset() { return OFFSET_OF(RawContext, isolate_); }
 
   intptr_t num_variables() const { return raw_ptr()->num_variables_; }
   static intptr_t num_variables_offset() {
     return OFFSET_OF(RawContext, num_variables_);
@@ skipping 1660 matching lines @@
 }
 
 
 void Context::SetAt(intptr_t index, const Instance& value) const {
   StorePointer(InstanceAddr(index), value.raw());
 }
 
 }  // namespace dart
 
 #endif  // VM_OBJECT_H_