[builtins] Turn LoadIC_Miss and LoadIC_Slow builtins to TurboFan code stubs.

src/ic/ic.cc

Index: src/ic/ic.cc
diff --git a/src/ic/ic.cc b/src/ic/ic.cc
index eee7d6993445403d7734782091bb394bfcb75ce6..841a1869e8e0838b97a0d62f73f040c5eb042c2f 100644
--- a/src/ic/ic.cc
+++ b/src/ic/ic.cc
@@ -448,6 +448,10 @@ void CallIC::Clear(Isolate* isolate, Code* host, CallICNexus* nexus) {
   }
 }
 
+Handle<Code> LoadIC::slow_stub() const {
+  LoadICSlowStub stub(isolate());
+  return stub.GetCode();
+}
 
 void LoadIC::Clear(Isolate* isolate, Code* host, LoadICNexus* nexus) {
   if (IsCleared(nexus)) return;