Deoptimization can occur at Dart calls (includes native calls to C) but not at runtime calls. This …

runtime/vm/intermediate_language.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_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 566 matching lines @@
   const Array& argument_names() const { return ast_node_.arguments()->names(); }
   intptr_t token_pos() const { return ast_node_.token_pos(); }
 
   virtual intptr_t ArgumentCount() const { return arguments_->length(); }
   PushArgumentInstr* ArgumentAt(intptr_t index) const {
     return (*arguments_)[index];
   }
 
   virtual void PrintOperandsTo(BufferFormatter* f) const;
 
-  virtual bool CanDeoptimize() const { return false; }
+  virtual bool CanDeoptimize() const { return true; }
   virtual intptr_t ResultCid() const { return kDynamicCid; }
 
  private:
   const ClosureCallNode& ast_node_;
   ZoneGrowableArray<PushArgumentInstr*>* arguments_;
 
   DISALLOW_COPY_AND_ASSIGN(ClosureCallComp);
 };
 
 
@@ skipping 2584 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_