Fix main handling in dart2js and add tests.

dart/sdk/lib/_internal/compiler/implementation/warnings.dart

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of dart2js;
 
 const DONT_KNOW_HOW_TO_FIX = "";
 
 /**
  * The messages in this file should meet the following guide lines:
@@ skipping 1836 matching lines @@
           "main() => foo(x: 1 y: 2);",
         ]);
 
   static const MessageKind MISSING_TOKEN_AFTER_THIS = const MessageKind(
       "Expected '#{token}' after this.",
       // See [MISSING_TOKEN_BEFORE_THIS], we don't have enough information to
       // give a good suggestion.
       howToFix: DONT_KNOW_HOW_TO_FIX,
       examples: const ["main(x) {x}"]);
 
+  static const MessageKind CONSIDER_ANALYZE_ALL = const MessageKind(
+      "Could not find '#{main}'.  Nothing will be analyzed.",
+      howToFix: "Try using '--analyze-all' to analyze everything.",
+      examples: const ['']);
+
+  static const MessageKind MISSING_MAIN = const MessageKind(
+      "Could not find '#{main}'.",
+      howToFix: "Try adding a method named '#{main}' to your program."
+      /* No example, test uses '--analyze-only' which will produce the above
+       * message [CONSIDER_ANALYZE_ALL].  An example for a human operator would
+       * be an empty file. */);
+
+  static const MessageKind MAIN_NOT_A_FUNCTION = const MessageKind(
+      "'#{main}' is not a function.",
+      howToFix: DONT_KNOW_HOW_TO_FIX, /* Don't state the obvious. */
+      examples: const ['var main;']);
+
+  static const MessageKind MAIN_WITH_EXTRA_PARAMETER = const MessageKind(
+      "'#{main}' cannot have more than two parameters.",
+      howToFix: DONT_KNOW_HOW_TO_FIX, /* Don't state the obvious. */
+      examples: const ['main(a, b, c) {}']);
+
   static const MessageKind COMPILER_CRASHED = const MessageKind(
       "The compiler crashed when compiling this element.");
 
   static const MessageKind PLEASE_REPORT_THE_CRASH = const MessageKind('''
 The compiler is broken.
 
 When compiling the above element, the compiler crashed. It is not
 possible to tell if this is caused by a problem in your program or
 not. Regardless, the compiler should not crash.
 
@@ skipping 218 matching lines @@
   static String convertToString(value) {
     if (value is ErrorToken) {
       // Shouldn't happen.
       return value.assertionMessage;
     } else if (value is Token) {
       value = value.value;
     }
     return '$value';
   }
 }