Remove unused/not working function tracing flag and functionality.

runtime/vm/stub_code.h

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_STUB_CODE_H_
 #define VM_STUB_CODE_H_
 
 #include "vm/allocation.h"
 #include "vm/assembler.h"
 
@@ skipping 38 matching lines @@
 // List of stubs created per isolate, these stubs could potentially contain
 // embedded objects and hence cannot be shared across isolates.
 #define STUB_CODE_LIST(V)                                                      \
   V(InvokeDartCode)                                                            \
   V(AllocateContext)                                                           \
   V(UpdateStoreBuffer)                                                         \
   V(OneArgCheckInlineCache)                                                    \
   V(TwoArgsCheckInlineCache)                                                   \
   V(ThreeArgsCheckInlineCache)                                                 \
   V(MegamorphicCall)                                                           \
+  V(OptimizeFunction)                                                          \
   V(BreakpointDynamic)                                                         \
   V(EqualityWithNullArg)                                                       \
 
 // class StubEntry is used to describe stub methods generated in dart to
 // abstract out common code executed from generated dart code.
 class StubEntry {
  public:
   StubEntry(const char* name, const Code& code);
   ~StubEntry() {}
 
@@ skipping 116 matching lines @@
   static void GenerateNArgsCheckInlineCacheStub(Assembler* assembler,
                                                 intptr_t num_args);
   static void GenerateUsageCounterIncrement(Assembler* assembler,
                                             Register ic_reg,
                                             Register temp_reg);
 };
 
 }  // namespace dart
 
 #endif  // VM_STUB_CODE_H_