Make CTX allocatable by the register allocator.

runtime/vm/parser.cc

Index: runtime/vm/parser.cc
===================================================================
--- runtime/vm/parser.cc	(revision 41393)
+++ runtime/vm/parser.cc	(working copy)
@@ -864,10 +864,8 @@
   if (parsed_function->has_expression_temp_var()) {
     node_sequence->scope()->AddVariable(parsed_function->expression_temp_var());
   }
-  if (parsed_function->has_saved_current_context_var()) {
-    node_sequence->scope()->AddVariable(
-        parsed_function->saved_current_context_var());
-  }
+  node_sequence->scope()->AddVariable(
+      parsed_function->current_context_var());
   if (parsed_function->has_finally_return_temp_var()) {
     node_sequence->scope()->AddVariable(
         parsed_function->finally_return_temp_var());
@@ -1068,9 +1066,7 @@
   if (parsed_function->has_expression_temp_var()) {
     body->scope()->AddVariable(parsed_function->expression_temp_var());
   }
-  if (parsed_function->has_saved_current_context_var()) {
-    body->scope()->AddVariable(parsed_function->saved_current_context_var());
-  }
+  body->scope()->AddVariable(parsed_function->current_context_var());
   if (parsed_function->has_finally_return_temp_var()) {
     body->scope()->AddVariable(parsed_function->finally_return_temp_var());
   }
@@ -1387,7 +1383,6 @@
   ASSERT(!owner.IsNull());
   AstNode* result = NULL;
   if (owner.IsSignatureClass() && name.Equals(Symbols::Call())) {
-    EnsureSavedCurrentContext();
     result = new ClosureCallNode(token_pos, getter_call, args);
   } else {
     result = BuildClosureCall(token_pos, getter_call, args);
@@ -8695,19 +8690,6 @@
 }
 
 
-void Parser::EnsureSavedCurrentContext() {
-  // Used later by the flow_graph_builder to save current context.
-  if (!parsed_function()->has_saved_current_context_var()) {
-    LocalVariable* temp = new(I) LocalVariable(
-        current_function().token_pos(),
-        Symbols::SavedCurrentContextVar(),
-        Type::ZoneHandle(I, Type::DynamicType()));
-    ASSERT(temp != NULL);
-    parsed_function()->set_saved_current_context_var(temp);
-  }
-}
-
-
 LocalVariable* Parser::CreateTempConstVariable(intptr_t token_pos,
                                                const char* s) {
   char name[64];