Remove broken %_Log functionality.

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index ee143f9fe4268c8e40fb2edf7c57e3eeb5627d32..d9893d62109a7db7fe8e13958462a2cc26e79924 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -1205,10 +1205,6 @@ class MacroAssembler: public Assembler {
                                Label* miss,
                                bool miss_on_bound_function = false);
 
-  // Generates code for reporting that an illegal operation has
-  // occurred.
-  void IllegalOperation(int num_arguments);
-
   // Picks out an array index from the hash field.
   // Register use:
   //   hash - holds the index's hash. Clobbered.