Remove special frontend for callbacks with slow-mode holders.

src/x64/stub-cache-x64.cc

Index: src/x64/stub-cache-x64.cc
diff --git a/src/x64/stub-cache-x64.cc b/src/x64/stub-cache-x64.cc
index 69781ebea1551a7e8c18906b3fe8e755ffd1833e..1d4e4d6c7337e939d17182e60286ca9fd45c204c 100644
--- a/src/x64/stub-cache-x64.cc
+++ b/src/x64/stub-cache-x64.cc
@@ -748,54 +748,6 @@ void NamedStoreHandlerCompiler::FrontendFooter(Handle<Name> name, Label* miss) {
 }
 
 
-Register NamedLoadHandlerCompiler::CallbackFrontend(Register object_reg,
-                                                    Handle<Name> name,
-                                                    Handle<Object> callback) {
-  Label miss;
-
-  Register reg = FrontendHeader(object_reg, name, &miss);
-
-  if (!holder()->HasFastProperties()) {
-    DCHECK(!holder()->IsGlobalObject());
-    DCHECK(!reg.is(scratch2()));
-    DCHECK(!reg.is(scratch3()));
-    DCHECK(!reg.is(scratch4()));
-
-    // Load the properties dictionary.
-    Register dictionary = scratch4();
-    __ movp(dictionary, FieldOperand(reg, JSObject::kPropertiesOffset));
-
-    // Probe the dictionary.
-    Label probe_done;
-    NameDictionaryLookupStub::GeneratePositiveLookup(masm(),
-                                                     &miss,
-                                                     &probe_done,
-                                                     dictionary,
-                                                     this->name(),
-                                                     scratch2(),
-                                                     scratch3());
-    __ bind(&probe_done);
-
-    // If probing finds an entry in the dictionary, scratch3 contains the
-    // index into the dictionary. Check that the value is the callback.
-    Register index = scratch3();
-    const int kElementsStartOffset =
-        NameDictionary::kHeaderSize +
-        NameDictionary::kElementsStartIndex * kPointerSize;
-    const int kValueOffset = kElementsStartOffset + kPointerSize;
-    __ movp(scratch2(),
-            Operand(dictionary, index, times_pointer_size,
-                    kValueOffset - kHeapObjectTag));
-    __ Move(scratch3(), callback, RelocInfo::EMBEDDED_OBJECT);
-    __ cmpp(scratch2(), scratch3());
-    __ j(not_equal, &miss);
-  }
-
-  FrontendFooter(name, &miss);
-  return reg;
-}
-
-
 void NamedLoadHandlerCompiler::GenerateLoadField(
     Register reg, FieldIndex field, Representation representation) {
   if (!reg.is(receiver())) __ movp(receiver(), reg);