Simple fixes

runtime/vm/jit_optimizer.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/jit_optimizer.h"
 
 #include "vm/bit_vector.h"
 #include "vm/branch_optimizer.h"
 #include "vm/cha.h"
 #include "vm/compiler.h"
@@ skipping 2973 matching lines @@
         unboxed_field = true;
       }
     }
     if (!unboxed_field) {
       // TODO(srdjan): Instead of aborting pass this field to the mutator thread
       // so that it can:
       // - set it to unboxed
       // - deoptimize dependent code.
       if (Compiler::IsBackgroundCompilation()) {
         isolate()->AddDeoptimizingBoxedField(field);
-        Compiler::AbortBackgroundCompilation(Thread::kNoDeoptId);
+        Compiler::AbortBackgroundCompilation(Thread::kNoDeoptId,
+            "Unboxing instance field while compiling");
         UNREACHABLE();
       }
       if (FLAG_trace_optimization || FLAG_trace_field_guards) {
         THR_Print("Disabling unboxing of %s\n", field.ToCString());
         if (!setter.IsNull()) {
           OS::Print("  setter usage count: %" Pd "\n", setter.usage_counter());
         }
         if (!getter.IsNull()) {
           OS::Print("  getter usage count: %" Pd "\n", getter.usage_counter());
         }
@@ skipping 125 matching lines @@
 
   // Discard the environment from the original instruction because the store
   // can't deoptimize.
   instr->RemoveEnvironment();
   ReplaceCall(instr, store);
   return true;
 }
 
 
 }  // namespace dart