X87: [runtime] Implement %_ToLength via ToLengthStub.

src/x87/interface-descriptors-x87.cc

Index: src/x87/interface-descriptors-x87.cc
diff --git a/src/x87/interface-descriptors-x87.cc b/src/x87/interface-descriptors-x87.cc
index dab5156fe35ac906a6d1041ab6e7e62d9d3aa242..c894d4c48ce543a29ea6ffa294775220550bcaa3 100644
--- a/src/x87/interface-descriptors-x87.cc
+++ b/src/x87/interface-descriptors-x87.cc
@@ -106,6 +106,10 @@ void ToNumberDescriptor::InitializePlatformSpecific(
 
 
 // static
+const Register ToLengthDescriptor::ReceiverRegister() { return eax; }
+
+
+// static
 const Register ToStringDescriptor::ReceiverRegister() { return eax; }