We can throw an exception but we cannot deoptimize at a runtime call.

runtime/vm/flow_graph_compiler_x64.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_FLOW_GRAPH_COMPILER_X64_H_
 #define VM_FLOW_GRAPH_COMPILER_X64_H_
 
 #ifndef VM_FLOW_GRAPH_COMPILER_H_
 #error Include flow_graph_compiler.h instead of flow_graph_compiler_x64.h.
 #endif
@@ skipping 59 matching lines @@
 
   void LoadDoubleOrSmiToXmm(XmmRegister result,
                             Register reg,
                             Register temp,
                             Label* not_double_or_smi);
 
   // Returns 'true' if code generation for this function is complete, i.e.,
   // no fall-through to regular code is needed.
   bool TryIntrinsify();
 
-  void GenerateCallRuntime(intptr_t deopt_id,
-                           intptr_t token_pos,
+  void GenerateCallRuntime(intptr_t token_pos,
                            const RuntimeEntry& entry,
                            LocationSummary* locs);
 
   void GenerateCall(intptr_t token_pos,
                     const ExternalLabel* label,
                     PcDescriptors::Kind kind,
                     LocationSummary* locs);
 
   void GenerateDartCall(intptr_t deopt_id,
                         intptr_t token_pos,
                         const ExternalLabel* label,
                         PcDescriptors::Kind kind,
                         LocationSummary* locs);
 
-  void GenerateAssertAssignable(intptr_t deopt_id,
-                                intptr_t token_pos,
+  void GenerateAssertAssignable(intptr_t token_pos,
                                 const AbstractType& dst_type,
                                 const String& dst_name,
                                 LocationSummary* locs);
 
-  void GenerateInstanceOf(intptr_t deopt_id,
-                          intptr_t token_pos,
+  void GenerateInstanceOf(intptr_t token_pos,
                           const AbstractType& type,
                           bool negate_result,
                           LocationSummary* locs);
 
   void GenerateInstanceCall(intptr_t deopt_id,
                             intptr_t token_pos,
                             const String& function_name,
                             intptr_t argument_count,
                             const Array& argument_names,
                             intptr_t checked_argument_count,
@@ skipping 208 matching lines @@
   // that should be used when deoptimizing we store it in this variable.
   // In future AddDeoptStub should be moved out of the instruction template.
   Environment* pending_deoptimization_env_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphCompiler);
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_COMPILER_X64_H_