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

runtime/vm/flow_graph_builder_test.cc

 // Copyright (c) 2016, 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/compiler.h"
 #include "vm/dart_api_impl.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_builder.h"
 #include "vm/intermediate_language.h"
 #include "vm/unit_test.h"
@@ skipping 42 matching lines @@
     const bool optimized = false;
 
     const Function& function =
         Function::Handle(GetFunction(root_lib_, function_name));
     ZoneGrowableArray<const ICData*>* ic_data_array =
         new ZoneGrowableArray<const ICData*>();
     ParsedFunction* parsed_function =
         new ParsedFunction(thread_, Function::ZoneHandle(function.raw()));
     Parser::ParseFunction(parsed_function);
     parsed_function->AllocateVariables();
-    FlowGraphBuilder builder(*parsed_function, *ic_data_array, NULL,
-                             Compiler::kNoOSRDeoptId);
+    FlowGraphBuilder builder(*parsed_function, *ic_data_array,
+                             /* not building var desc */ NULL,
+                             /* not inlining */ NULL, Compiler::kNoOSRDeoptId);
     graph_ = builder.BuildGraph();
     EXPECT(graph_ != NULL);
     blocks_ = graph_->CodegenBlockOrder(optimized);
     EXPECT(blocks_ != NULL);
     graph_name_ = function_name;
     EXPECT(graph_name_ != NULL);
   }
 
   // Expect to find an instance call at |line| and |column|.
   void InstanceCallAt(intptr_t line,
@@ skipping 706 matching lines @@
   EXPECT(TokenPosition(9).ToSynthetic().IsSynthetic());
   EXPECT(!TokenPosition(-1).FromSynthetic().IsSynthetic());
   EXPECT(!TokenPosition::kNoSource.IsSynthetic());
   EXPECT(!TokenPosition::kLast.IsSynthetic());
   EXPECT(SyntheticRoundTripTest(TokenPosition(0)));
   EXPECT(SyntheticRoundTripTest(TokenPosition::kMaxSource));
   EXPECT(SyntheticRoundTripTest(TokenPosition::kMinSource));
 }
 
 }  // namespace dart