Allocate the environment's location backing store during register allocation.

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 bf594de0a8710ad5df19cb3291d86f517aec06fb..bdc64541de859342e6b7efa39850459c91d73ff4 100644
--- a/runtime/vm/il_printer.cc
+++ b/runtime/vm/il_printer.cc
@@ -775,7 +775,7 @@ void Environment::PrintTo(BufferFormatter* f) const {
   for (intptr_t i = 0; i < values_.length(); ++i) {
     if (i > 0) f->Print(", ");
     values_[i]->PrintTo(f);
-    if ((i < locations_.length()) && !locations_[i].IsInvalid()) {
+    if ((locations_ != NULL) && !locations_[i].IsInvalid()) {
       f->Print(" [");
       locations_[i].PrintTo(f);
       f->Print("]");