Remove --reject_named_argument_as_positional flag from the VM.

runtime/vm/flow_graph_compiler_x64.cc

Index: runtime/vm/flow_graph_compiler_x64.cc
===================================================================
--- runtime/vm/flow_graph_compiler_x64.cc	(revision 14213)
+++ runtime/vm/flow_graph_compiler_x64.cc	(working copy)
@@ -20,7 +20,6 @@
 
 DECLARE_FLAG(bool, print_ast);
 DECLARE_FLAG(bool, print_scopes);
-DECLARE_FLAG(bool, reject_named_argument_as_positional);
 DECLARE_FLAG(bool, trace_functions);
 DECLARE_FLAG(bool, use_sse41);
 DEFINE_FLAG(bool, trap_on_deoptimization, false, "Trap on deoptimization.");
@@ -698,11 +697,6 @@
   __ j(POSITIVE, &loop, Assembler::kNearJump);
 
   // Copy or initialize optional named arguments.
-
-  if (!FLAG_reject_named_argument_as_positional) {
-    // Treat optional positional parameters as optional named parameters.
-    num_opt_named_params += num_opt_pos_params;
-  }
   const Immediate raw_null =
       Immediate(reinterpret_cast<intptr_t>(Object::null()));
   Label all_arguments_processed;
@@ -738,13 +732,6 @@
     for (int i = 0; i < num_opt_named_params; i++) {
       Label load_default_value, assign_optional_parameter, next_parameter;
       const int param_pos = opt_param_position[i];
-      if (!FLAG_reject_named_argument_as_positional) {
-        // Handle this optional parameter only if k or fewer positional
-        // arguments have been passed, where k is the position of this optional
-        // parameter in the formal parameter list.
-        __ cmpq(RCX, Immediate(param_pos));
-        __ j(GREATER, &next_parameter, Assembler::kNearJump);
-      }
       // Check if this named parameter was passed in.
       __ movq(RAX, Address(RDI, 0));  // Load RAX with the name of the argument.
       ASSERT(opt_param[i]->name().IsSymbol());
@@ -781,7 +768,6 @@
     __ cmpq(Address(RDI, 0), raw_null);
     __ j(EQUAL, &all_arguments_processed, Assembler::kNearJump);
   } else if (num_opt_pos_params > 0) {
-    ASSERT(FLAG_reject_named_argument_as_positional);
     // Number of positional args is the second Smi in descriptor array (R10).
     __ movq(RCX, FieldAddress(R10, Array::data_offset() + (1 * kWordSize)));
     __ SmiUntag(RCX);