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

src/arm64/builtins-arm64.cc

Index: src/arm64/builtins-arm64.cc
diff --git a/src/arm64/builtins-arm64.cc b/src/arm64/builtins-arm64.cc
index 61b7e5fd780d902aa9a9bbbae5113ef92675052b..44bfc1762d83cf327db52032b1cf54e3719be5be 100644
--- a/src/arm64/builtins-arm64.cc
+++ b/src/arm64/builtins-arm64.cc
@@ -1977,6 +1977,16 @@ void PrepareForTailCall(MacroAssembler* masm, Register args_reg,
   DCHECK(!AreAliased(args_reg, scratch1, scratch2, scratch3));
   Comment cmnt(masm, "[ PrepareForTailCall");
 
+  // Prepare for tail call only if ES2015 tail call elimination is enabled.
+  Label done;
+  ExternalReference is_tail_call_elimination_enabled =
+      ExternalReference::is_tail_call_elimination_enabled_address(
+          masm->isolate());
+  __ Mov(scratch1, Operand(is_tail_call_elimination_enabled));
+  __ Ldrb(scratch1, MemOperand(scratch1));
+  __ Cmp(scratch1, Operand(0));
+  __ B(eq, &done);
+
   // Drop possible interpreter handler/stub frame.
   {
     Label no_interpreter_frame;
@@ -2017,6 +2027,7 @@ void PrepareForTailCall(MacroAssembler* masm, Register args_reg,
   ParameterCount callee_args_count(args_reg);
   __ PrepareForTailCall(callee_args_count, caller_args_count_reg, scratch2,
                         scratch3);
+  __ bind(&done);
 }
 }  // namespace