Adjusts dart2js backend to handle method type arguments.

pkg/compiler/lib/src/commandline_options.dart

Index: pkg/compiler/lib/src/commandline_options.dart
diff --git a/pkg/compiler/lib/src/commandline_options.dart b/pkg/compiler/lib/src/commandline_options.dart
index 9c0c2449cec994a30fb9e39e92453f03d22da771..f3828411f8db98ab5cd04a59019e84386d83af22 100644
--- a/pkg/compiler/lib/src/commandline_options.dart
+++ b/pkg/compiler/lib/src/commandline_options.dart
@@ -52,6 +52,17 @@ class Flags {
   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';
 }