Move all main methods to tool/.

pkg/front_end/lib/src/fasta/parser/parser_main.dart

Index: pkg/front_end/lib/src/fasta/parser/parser_main.dart
diff --git a/pkg/front_end/lib/src/fasta/parser/main.dart b/pkg/front_end/lib/src/fasta/parser/parser_main.dart
similarity index 96%
rename from pkg/front_end/lib/src/fasta/parser/main.dart
rename to pkg/front_end/lib/src/fasta/parser/parser_main.dart
index df3bfc7f2885257136e06db917df09f8ea4acc72..215bddf60a6fdaa2b926a5db6e31d55079e080c5 100644
--- a/pkg/front_end/lib/src/fasta/parser/main.dart
+++ b/pkg/front_end/lib/src/fasta/parser/parser_main.dart
@@ -30,7 +30,7 @@ class DebugListener extends Listener {
   }
 }
 
-main(List<String> arguments) async {
+mainEntryPoint(List<String> arguments) async {
   for (String argument in arguments) {
     if (argument.startsWith("@")) {
       Uri uri = Uri.base.resolve(argument.substring(1));