Check that environments assigned via AssignEnvironment are actually used.

src/arm/lithium-codegen-arm.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 765 matching lines @@
                                        LOperand* context) {
   LoadContextFromDeferred(context);
   __ CallRuntimeSaveDoubles(id);
   RecordSafepointWithRegisters(
       instr->pointer_map(), argc, Safepoint::kNoLazyDeopt);
 }
 
 
 void LCodeGen::RegisterEnvironmentForDeoptimization(LEnvironment* environment,
                                                     Safepoint::DeoptMode mode) {
+  environment->set_has_been_used();
   if (!environment->HasBeenRegistered()) {
     // Physical stack frame layout:
     // -x ............. -4  0 ..................................... y
     // [incoming arguments] [spill slots] [pushed outgoing arguments]
 
     // Layout of the environment:
     // 0 ..................................................... size-1
     // [parameters] [locals] [expression stack including arguments]
 
     // Layout of the translation:
@@ skipping 5047 matching lines @@
   __ ldr(result, FieldMemOperand(scratch,
                                  FixedArray::kHeaderSize - kPointerSize));
   __ bind(deferred->exit());
   __ bind(&done);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal