[es6] Add a flag to the Isolate that defines whether ES2015 tail call elimination is enabled or not.

src/assembler.cc

 // Copyright (c) 1994-2006 Sun Microsystems Inc.
 // All Rights Reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 // - Redistributions of source code must retain the above copyright notice,
 // this list of conditions and the following disclaimer.
 //
@@ skipping 1614 matching lines @@
 ExternalReference ExternalReference::ForDeoptEntry(Address entry) {
   return ExternalReference(entry);
 }
 
 
 ExternalReference ExternalReference::cpu_features() {
   DCHECK(CpuFeatures::initialized_);
   return ExternalReference(&CpuFeatures::supported_);
 }
 
+ExternalReference ExternalReference::is_tail_call_elimination_enabled_address(
+    Isolate* isolate) {
+  return ExternalReference(isolate->is_tail_call_elimination_enabled_address());
+}
 
 ExternalReference ExternalReference::debug_is_active_address(
     Isolate* isolate) {
   return ExternalReference(isolate->debug()->is_active_address());
 }
 
 
 ExternalReference ExternalReference::debug_after_break_target_address(
     Isolate* isolate) {
   return ExternalReference(isolate->debug()->after_break_target_address());
@@ skipping 431 matching lines @@
 
 
 void Assembler::DataAlign(int m) {
   DCHECK(m >= 2 && base::bits::IsPowerOfTwo32(m));
   while ((pc_offset() & (m - 1)) != 0) {
     db(0);
   }
 }
 }  // namespace internal
 }  // namespace v8