Adjusts dart2js backend to handle method type arguments.

pkg/compiler/lib/src/js_backend/backend.dart

 // Copyright (c) 2012, 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 js_backend;
 
 const VERBOSE_OPTIMIZER_HINTS = false;
 
 class JavaScriptItemCompilationContext extends ItemCompilationContext {
   final Set<HInstruction> boundsChecked = new Set<HInstruction>();
@@ skipping 2720 matching lines @@
           }
           break;
         case TypeUseKind.CATCH_TYPE:
           onIsCheck(type, transformed);
           break;
         case TypeUseKind.TYPE_LITERAL:
           backend.customElementsAnalysis.registerTypeLiteral(type);
           if (type.isTypedef) {
             backend.compiler.world.allTypedefs.add(type.element);
           }
-          if (type.isTypeVariable) {
+          if (type.isTypeVariable && type is! MethodTypeVariableType) {
+            // GENERIC_METHODS: The `is!` test above filters away method type
+            // variables, because they have the value `dynamic` with the
+            // incomplete support for generic methods offered with
+            // '--generic-method-syntax'. This must be revised in order to
+            // support generic methods fully.
             ClassElement cls = type.element.enclosingClass;
             backend.rti.registerClassUsingTypeVariableExpression(cls);
             registerBackendImpact(transformed, impacts.typeVariableExpression);
           }
           hasTypeLiteral = true;
           break;
       }
     }
 
     if (hasAsCast) {
@@ skipping 303 matching lines @@
 
   @override
   void onImpactUsed(ImpactUseCase impactUse) {
     if (impactUse == DeferredLoadTask.IMPACT_USE && !supportSerialization) {
       // TODO(johnniwinther): Allow emptying when serialization has been
       // performed.
       resolution.emptyCache();
     }
   }
 }