Refactor generating lazy deoptimization descriptors.

runtime/vm/flow_graph.cc

Index: runtime/vm/flow_graph.cc
===================================================================
--- runtime/vm/flow_graph.cc	(revision 40149)
+++ runtime/vm/flow_graph.cc	(working copy)
@@ -766,16 +766,6 @@
                         *env,
                         num_non_copied_params_,
                         &parsed_function_);
-  // TODO(fschneider): Add predicates CanEagerlyDeoptimize and
-  // CanLazilyDeoptimize to instructions to generally deal with instructions
-  // that have pushed arguments and input operands.
-  // Right now, closure calls are the only instructions that have both. They
-  // also don't have an eager deoptimziation point, so the environment attached
-  // here is only used for after the call.
-  if (instr->IsClosureCall()) {
-    deopt_env = deopt_env->DeepCopy(isolate(),
-                                    deopt_env->Length() - instr->InputCount());
-  }
   instr->SetEnvironment(deopt_env);
   for (Environment::DeepIterator it(deopt_env); !it.Done(); it.Advance()) {
     Value* use = it.CurrentValue();