[runtime] Implement %_ToLength via ToLengthStub.

src/arm64/code-stubs-arm64.cc

Index: src/arm64/code-stubs-arm64.cc
diff --git a/src/arm64/code-stubs-arm64.cc b/src/arm64/code-stubs-arm64.cc
index fc75e082baeffe8fc47bb51f9b893156c045f705..0a7b4752656e9c2c589e31d0d338a5d4b9d8c5c3 100644
--- a/src/arm64/code-stubs-arm64.cc
+++ b/src/arm64/code-stubs-arm64.cc
@@ -3914,6 +3914,21 @@ void ToNumberStub::Generate(MacroAssembler* masm) {
 }
 
 
+void ToLengthStub::Generate(MacroAssembler* masm) {
+  // The ToLength stub takes one argument in x0.
+  Label not_smi;
+  __ JumpIfNotSmi(x0, &not_smi);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ Tst(x0, x0);
+  __ Csel(x0, x0, Operand(0), ge);
+  __ Ret();
+  __ Bind(&not_smi);
+
+  __ Push(x0);  // Push argument.
+  __ TailCallRuntime(Runtime::kToLength, 1, 1);
+}
+
+
 void ToStringStub::Generate(MacroAssembler* masm) {
   // The ToString stub takes one argument in x0.
   Label is_number;