Introduce --log-external-callbacks flag apart from --log-timer-events.

src/ia32/macro-assembler-ia32.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1902 matching lines @@
   ExternalReference limit_address =
       ExternalReference::handle_scope_limit_address();
   ExternalReference level_address =
       ExternalReference::handle_scope_level_address();
 
   // Allocate HandleScope in callee-save registers.
   mov(ebx, Operand::StaticVariable(next_address));
   mov(edi, Operand::StaticVariable(limit_address));
   add(Operand::StaticVariable(level_address), Immediate(1));
 
-  if (FLAG_log_timer_events) {
+  if (FLAG_log_external_callbacks) {
     FrameScope frame(this, StackFrame::MANUAL);
     PushSafepointRegisters();
     PrepareCallCFunction(0, eax);
     CallCFunction(ExternalReference::log_enter_external_function(isolate()), 0);
     PopSafepointRegisters();
   }
 
   // Call the api function.
   call(function_address, RelocInfo::RUNTIME_ENTRY);
 
-  if (FLAG_log_timer_events) {
+  if (FLAG_log_external_callbacks) {
     FrameScope frame(this, StackFrame::MANUAL);
     PushSafepointRegisters();
     PrepareCallCFunction(0, eax);
     CallCFunction(ExternalReference::log_leave_external_function(isolate()), 0);
     PopSafepointRegisters();
   }
 
   if (!kReturnHandlesDirectly) {
     // PrepareCallApiFunction saved pointer to the output slot into
     // callee-save register esi.
@@ skipping 1055 matching lines @@
   j(not_equal, call_runtime);
 
   mov(ecx, FieldOperand(ebx, Map::kPrototypeOffset));
   cmp(ecx, isolate()->factory()->null_value());
   j(not_equal, &next);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_IA32