[runtime] Implement %_ToLength via ToLengthStub.

src/arm/code-stubs-arm.cc

Index: src/arm/code-stubs-arm.cc
diff --git a/src/arm/code-stubs-arm.cc b/src/arm/code-stubs-arm.cc
index 35928107f2b78551156c05c6cfa3a6190d8a06ce..d85ebdb114c76ba4a3f9a9796d2154814e678ab8 100644
--- a/src/arm/code-stubs-arm.cc
+++ b/src/arm/code-stubs-arm.cc
@@ -3168,6 +3168,21 @@ void ToNumberStub::Generate(MacroAssembler* masm) {
 }
 
 
+void ToLengthStub::Generate(MacroAssembler* masm) {
+  // The ToLength stub takes one argument in r0.
+  Label not_smi;
+  __ JumpIfNotSmi(r0, &not_smi);
+  STATIC_ASSERT(kSmiTag == 0);
+  __ tst(r0, r0);
+  __ mov(r0, Operand(0), LeaveCC, lt);
+  __ Ret();
+  __ bind(&not_smi);
+
+  __ push(r0);  // Push argument.
+  __ TailCallRuntime(Runtime::kToLength, 1, 1);
+}
+
+
 void ToStringStub::Generate(MacroAssembler* masm) {
   // The ToString stub takes one argument in r0.
   Label is_number;