[profiler] Do not log timer events when --prof is specified.

Now hopefully getting it right, but still leaving in the confusing
flag implications.

Bug: v8:6520,chromium:766162
Change-Id: Idc6dca012bf0c9777b4a75cf424410ce5914c885
Reviewed-on: https://chromium-review.googlesource.com/671022Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Jaroslav Sevcik <jarin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48082}

src/objects.cc

@@ -18691,7 +18691,7 @@ MaybeHandle<JSDate> JSDate::New(Handle<JSFunction> constructor,
 
 // static
 double JSDate::CurrentTimeValue(Isolate* isolate) {
-  if (FLAG_log_timer_events || FLAG_prof_cpp) LOG(isolate, CurrentTimeEvent());
+  if (FLAG_log_internal_timer_events) LOG(isolate, CurrentTimeEvent());
 
   // According to ECMA-262, section 15.9.1, page 117, the precision of
   // the number in a Date object representing a particular instant in