Adjusts dart2js backend to handle method type arguments.

pkg/compiler/lib/src/commandline_options.dart

 // Copyright (c) 2015, 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.
 
 library dart2js.cmdline.options;
 
 /// Commandline flags used in `dart2js.dart` and/or `apiimpl.dart`.
 class Flags {
   static const String allowMockCompilation = '--allow-mock-compilation';
   static const String allowNativeExtensions = '--allow-native-extensions';
@@ skipping 34 matching lines @@
       '--experimental-trust-js-interop-type-annotations';
   static const String useContentSecurityPolicy = '--csp';
   static const String useCpsIr = '--use-cps-ir';
   static const String useNewSourceInfo = '--use-new-source-info';
   static const String verbose = '--verbose';
   static const String version = '--version';
 
   static const String conditionalDirectives = '--conditional-directives';
 
   // Experimental flags.
+
+  // Considerations about this feature (esp. locations where generalizations
+  // or changes are required for full support of generic methods) are marked
+  // with 'GENERIC_METHODS'. The approach taken is to parse generic methods,
+  // introduce AST nodes for them, generate corresponding types (such that
+  // front end treatment is consistent with the code that programmers wrote),
+  // but considering all method type variables to have bound `dynamic` no
+  // matter which bound they have syntactically (such that their value as types
+  // is unchecked), and then replacing method type variables by a `DynamicType`
+  // (such that the backend does not need to take method type arguments into
+  // account).
   static const String genericMethodSyntax = '--generic-method-syntax';
 }
 
 class Option {
   static const String showPackageWarnings =
       '${Flags.showPackageWarnings}|${Flags.showPackageWarnings}=.*';
 }