Remember deopt-id -> context-level mappings in var descriptors.

runtime/vm/flow_graph_compiler.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 RUNTIME_VM_FLOW_GRAPH_COMPILER_H_
 #define RUNTIME_VM_FLOW_GRAPH_COMPILER_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 #include "vm/code_descriptors.h"
@@ skipping 439 matching lines @@
                        Label* match_found,
                        intptr_t deopt_id,
                        TokenPosition token_index,
                        LocationSummary* locs,
                        bool complete,
                        intptr_t total_ic_calls);
 
   Condition EmitEqualityRegConstCompare(Register reg,
                                         const Object& obj,
                                         bool needs_number_check,
-                                        TokenPosition token_pos);
+                                        TokenPosition token_pos,
+                                        intptr_t deopt_id);
   Condition EmitEqualityRegRegCompare(Register left,
                                       Register right,
                                       bool needs_number_check,
-                                      TokenPosition token_pos);
+                                      TokenPosition token_pos,
+                                      intptr_t deopt_id);
 
   bool NeedsEdgeCounter(TargetEntryInstr* block);
 
   void EmitEdgeCounter(intptr_t edge_id);
 #endif  // !defined(TARGET_ARCH_DBC)
   void EmitCatchEntryState(
       Environment* env = NULL,
       intptr_t try_index = CatchClauseNode::kInvalidTryIndex);
 
   void EmitCallsiteMetaData(TokenPosition token_pos,
@@ skipping 363 matching lines @@
   ZoneGrowableArray<const ICData*>* deopt_id_to_ic_data_;
 
   Array& edge_counters_array_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphCompiler);
 };
 
 }  // namespace dart
 
 #endif  // RUNTIME_VM_FLOW_GRAPH_COMPILER_H_