Introduce nested deoptimization environments.

runtime/vm/il_printer.cc

Index: runtime/vm/il_printer.cc
diff --git a/runtime/vm/il_printer.cc b/runtime/vm/il_printer.cc
index 0dbd368065a07b03732a82733d34a111109cd755..1a1d8c033cf2655fd7d094067a5e9a0016bdc0a1 100644
--- a/runtime/vm/il_printer.cc
+++ b/runtime/vm/il_printer.cc
@@ -461,8 +461,8 @@ void GraphEntryInstr::PrintTo(BufferFormatter* f) const {
       constant_null()->PrintTo(f);
     }
     if (start_env() != NULL) {
-      for (intptr_t i = 0; i < start_env()->values().length(); ++i) {
-        Definition* def = start_env()->values()[i]->definition();
+      for (intptr_t i = 0; i < start_env()->Length(); ++i) {
+        Definition* def = start_env()->ValueAt(i)->definition();
         if (def->IsParameter()) {
           f->Print("\n      ");
           def->PrintTo(f);
@@ -804,6 +804,7 @@ void Environment::PrintTo(BufferFormatter* f) const {
     }
   }
   f->Print(" }");
+  if (outer_ != NULL) outer_->PrintTo(f);
 }
 
 }  // namespace dart