[runtime] Implement %_ToLength via ToLengthStub.

src/full-codegen/arm64/full-codegen-arm64.cc

Index: src/full-codegen/arm64/full-codegen-arm64.cc
diff --git a/src/full-codegen/arm64/full-codegen-arm64.cc b/src/full-codegen/arm64/full-codegen-arm64.cc
index c4a4136f63703667a45deee33e5af61b869a8acd..074982e83e896414da94a9d49260d639330a9008 100644
--- a/src/full-codegen/arm64/full-codegen-arm64.cc
+++ b/src/full-codegen/arm64/full-codegen-arm64.cc
@@ -3507,6 +3507,19 @@ void FullCodeGenerator::EmitNumberToString(CallRuntime* expr) {
 }
 
 
+void FullCodeGenerator::EmitToLength(CallRuntime* expr) {
+  ZoneList<Expression*>* args = expr->arguments();
+  DCHECK_EQ(1, args->length());
+
+  // Load the argument into x0 and convert it.
+  VisitForAccumulatorValue(args->at(0));
+
+  ToLengthStub stub(isolate());
+  __ CallStub(&stub);
+  context()->Plug(x0);
+}
+
+
 void FullCodeGenerator::EmitToString(CallRuntime* expr) {
   ZoneList<Expression*>* args = expr->arguments();
   DCHECK_EQ(1, args->length());