[ VM ] Send 'dart --help [--verbose]' output to stdout

This is consistent with the majority of other tools and the CLI
behavior.

Fixes dart-lang#46412

TEST=pkg/dartdev/test/commands/flag_test.dart

Change-Id: I45a3ddc9728e9cc1a273d4d5f11db74cb8104745
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/204661
Commit-Queue: Ben Konyi <bkonyi@google.com>
Reviewed-by: Ryan Macnak <rmacnak@google.com>

pkg/dartdev/test/commands/flag_test.dart

@@ -82,8 +82,8 @@ void help() {
     var result = p.runSync(['--help', '--verbose']);
 
     expect(result.exitCode, 0);
-    expect(result.stdout, isEmpty);
-    expect(result.stderr,
+    expect(result.stderr, isEmpty);
+    expect(result.stdout,
         contains('The following options are only used for VM development'));
   });
 
@@ -92,8 +92,8 @@ void help() {
     var result = p.runSync(['--help', '-v']);
 
     expect(result.exitCode, 0);
-    expect(result.stdout, isEmpty);
-    expect(result.stderr,
+    expect(result.stderr, isEmpty);
+    expect(result.stdout,
         contains('The following options are only used for VM development'));
   });
 

runtime/bin/main_options.cc

@@ -127,19 +127,19 @@ DEFINE_BOOL_OPTION_CB(hot_reload_rollback_test_mode,
                       hot_reload_rollback_test_mode_callback);
 
 void Options::PrintVersion() {
-  Syslog::PrintErr("Dart SDK version: %s\n", Dart_VersionString());
+  Syslog::Print("Dart SDK version: %s\n", Dart_VersionString());
 }
 
 // clang-format off
 void Options::PrintUsage() {
-  Syslog::PrintErr(
+  Syslog::Print(
       "Usage: dart [<vm-flags>] <dart-script-file> [<script-arguments>]\n"
       "\n"
       "Executes the Dart script <dart-script-file> with "
       "the given list of <script-arguments>.\n"
       "\n");
   if (!Options::verbose_option()) {
-    Syslog::PrintErr(
+    Syslog::Print(
 "Common VM flags:\n"
 "--enable-asserts\n"
 "  Enable assert statements.\n"
@@ -176,7 +176,7 @@ void Options::PrintUsage() {
 "--version\n"
 "  Print the SDK version.\n");
   } else {
-    Syslog::PrintErr(
+    Syslog::Print(
 "Supported options:\n"
 "--enable-asserts\n"
 "  Enable assert statements.\n"

runtime/vm/flags.cc

@@ -113,30 +113,29 @@ class Flag {
     }
     switch (type_) {
       case kBoolean: {
-        OS::PrintErr("%s: %s (%s)\n", name_,
-                     *this->bool_ptr_ ? "true" : "false", comment_);
+        OS::Print("%s: %s (%s)\n", name_, *this->bool_ptr_ ? "true" : "false",
+                  comment_);
         break;
       }
       case kInteger: {
-        OS::PrintErr("%s: %d (%s)\n", name_, *this->int_ptr_, comment_);
+        OS::Print("%s: %d (%s)\n", name_, *this->int_ptr_, comment_);
         break;
       }
       case kUint64: {
-        OS::PrintErr("%s: %" Pu64 " (%s)\n", name_, *this->uint64_ptr_,
-                     comment_);
+        OS::Print("%s: %" Pu64 " (%s)\n", name_, *this->uint64_ptr_, comment_);
         break;
       }
       case kString: {
         if (*this->charp_ptr_ != NULL) {
-          OS::PrintErr("%s: '%s' (%s)\n", name_, *this->charp_ptr_, comment_);
+          OS::Print("%s: '%s' (%s)\n", name_, *this->charp_ptr_, comment_);
         } else {
-          OS::PrintErr("%s: (null) (%s)\n", name_, comment_);
+          OS::Print("%s: (null) (%s)\n", name_, comment_);
         }
         break;
       }
       case kOptionHandler:
       case kFlagHandler: {
-        OS::PrintErr("%s: (%s)\n", name_, comment_);
+        OS::Print("%s: (%s)\n", name_, comment_);
         break;
       }
       default:
@@ -499,7 +498,7 @@ bool Flags::SetFlag(const char* name, const char* value, const char** error) {
 }
 
 void Flags::PrintFlags() {
-  OS::PrintErr("Flag settings:\n");
+  OS::Print("Flag settings:\n");
   for (intptr_t i = 0; i < num_flags_; ++i) {
     flags_[i]->Print();
   }