Beautify help output of flag names

Flags can be passed as "--any_flag" or "--any-flag". It seems that
people generally prefer the second form, but our help outputs the first
one. Avoid confusion by outputting the second form.

R=bmeurer@chromium.org

Change-Id: I21e07a7d2484ae78ccd27736f8373d53eb312818
Reviewed-on: https://chromium-review.googlesource.com/850692Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50376}

src/flags.cc

@@ -582,10 +582,13 @@ void FlagList::PrintHelp() {
         "    run the new debugging shell\n\n"
         "Options:\n";
 
-  for (size_t i = 0; i < num_flags; ++i) {
-    Flag* f = &flags[i];
-    os << "  --" << f->name() << " (" << f->comment() << ")\n"
-       << "        type: " << Type2String(f->type()) << "  default: " << *f
+  for (const Flag& f : flags) {
+    os << "  --";
+    for (const char* c = f.name(); *c != '\0'; ++c) {
+      os << NormalizeChar(*c);
+    }
+    os << " (" << f.comment() << ")\n"
+       << "        type: " << Type2String(f.type()) << "  default: " << f
        << "\n";
   }
 }