Partially revert r42319 to pacify tests.

runtime/vm/intermediate_language.cc

 // Copyright (c) 2013, 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/intermediate_language.h"
 
 #include "vm/bit_vector.h"
 #include "vm/cpu.h"
 #include "vm/dart_entry.h"
 #include "vm/flow_graph_allocator.h"
@@ skipping 2047 matching lines @@
   if (box_defn != NULL) {
     if (box_defn->value()->definition()->representation() == representation()) {
       return box_defn->value()->definition();
     } else {
       UnboxedIntConverterInstr* converter = new UnboxedIntConverterInstr(
           box_defn->value()->definition()->representation(),
           representation(),
           box_defn->value()->CopyWithType(),
           (representation() == kUnboxedInt32) ?
               GetDeoptId() : Isolate::kNoDeoptId);
-      if ((representation() == kUnboxedInt32) && is_truncating()) {
+      // TODO(vegorov): marking resulting converted as truncating when
+      // unboxing can't deoptimize is a work-around missing
+      // deoptimization environment in case when we insert converter after
+      // EliminateEnvironments and there is mismatch between predicates
+      // UnboxIntConverterInstr::CanDeoptimize and UnboxInt32::CanDeoptimize.
+      if ((representation() == kUnboxedInt32) &&
+          (is_truncating() || !CanDeoptimize())) {
         converter->mark_truncating();
       }
       flow_graph->InsertBefore(this, converter, env(), FlowGraph::kValue);
       return converter;
     }
   }
 
   return this;
 }
 
@@ skipping 1393 matching lines @@
     case Token::kTRUNCDIV: return 0;
     case Token::kMOD: return 1;
     default: UNIMPLEMENTED(); return -1;
   }
 }
 
 
 #undef __
 
 }  // namespace dart