Replace start_env with initial_definitions in GraphEntryInstr.

runtime/vm/flow_graph_inliner.cc

Index: runtime/vm/flow_graph_inliner.cc
diff --git a/runtime/vm/flow_graph_inliner.cc b/runtime/vm/flow_graph_inliner.cc
index 1d4cb8b70a7f568b53cf3ee9cd8b487e52d358f9..c60ee6d788403975ea86a1d4619d8604e09abac1 100644
--- a/runtime/vm/flow_graph_inliner.cc
+++ b/runtime/vm/flow_graph_inliner.cc
@@ -130,12 +130,16 @@ class CallSiteInliner : public FlowGraphVisitor {
       }
 
       // Replace formal parameters with actuals.
-      for (intptr_t i = 0; i < arguments->length(); ++i) {
-        Value* val = callee_graph->graph_entry()->start_env()->ValueAt(i);
-        ParameterInstr* param = val->definition()->AsParameter();
-        ASSERT(param != NULL);
-        param->ReplaceUsesWith((*arguments)[i]->definition());
+      intptr_t arg_index = 0;
+      GrowableArray<Definition*>* defns =
+          callee_graph->graph_entry()->initial_definitions();
+      for (intptr_t i = 0; i < defns->length(); ++i) {
+        ParameterInstr* param = (*defns)[i]->AsParameter();
+        if (param != NULL) {
+          param->ReplaceUsesWith((*arguments)[arg_index++]->definition());
+        }
       }
+      ASSERT(arg_index == arguments->length());
 
       // Replace callee's null constant with caller's null constant.
       callee_graph->graph_entry()->constant_null()->ReplaceUsesWith(