Adjusts dart2js backend to handle method type arguments.

pkg/compiler/lib/src/resolution/constructors.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.resolution.constructors;
 
 import '../common.dart';
 import '../common/resolution.dart' show Feature;
 import '../compiler.dart' show Compiler;
 import '../constants/constructors.dart'
@@ skipping 701 matching lines @@
           MessageKind.NOT_A_TYPE, {'node': node}, error.name, error);
       registry.registerFeature(Feature.THROW_RUNTIME_ERROR);
     }
     return new ConstructorResult.forError(ConstructorResultKind.INVALID_TYPE,
         error, new MalformedType(error, null));
   }
 
   ConstructorResult constructorResultForType(Node node, DartType type,
       {PrefixElement prefix}) {
     String name = type.name;
     if (type.isMalformed) {

[Johnni Winther, 2016/05/23 12:50:41]

If you move `if (type.isTypeVariable) ...` before `if (type.isMalformed) ...` no
other changes are needed.

[eernst, 2016/05/23 14:30:24]

Done.

-      return new ConstructorResult.forError(
-          ConstructorResultKind.INVALID_TYPE, type.element, type);
+      if (type is MalformedType) {
+        return new ConstructorResult.forError(
+            ConstructorResultKind.INVALID_TYPE, type.element, type);
+      } else {
+        // GENERIC_METHODS: This block provides thin support for generic
+        // methods: If a method type variable is used as a constructor, a
+        // warning is issued and code for a runtime error generated.
+        assert(type is MethodTypeVariableType);
+        MethodTypeVariableType methodTypeVariableType = type;
+        reporter.reportWarningMessage(
+            node,
+            MessageKind.CANNOT_INSTANTIATE_TYPE_VARIABLE,
+            { 'typeVariableName': methodTypeVariableType.name});
+        registry.registerFeature(Feature.THROW_RUNTIME_ERROR);
+        return new ConstructorResult.forError(
+            ConstructorResultKind.INVALID_TYPE,
+            methodTypeVariableType.toMalformedElement,
+            methodTypeVariableType);
+      }
     } else if (type.isInterfaceType) {
       return new ConstructorResult.forType(prefix, type);
     } else if (type.isTypedef) {
       return reportAndCreateErroneousConstructorElement(
           node,
           ConstructorResultKind.INVALID_TYPE,
           type,
           resolver.enclosingElement,
           name,
           MessageKind.CANNOT_INSTANTIATE_TYPEDEF,
@@ skipping 114 matching lines @@
     // constructors.
     return null;
   }
   // TODO(johnniwinther): Use [Name] for lookup.
   ConstructorElement constructor = cls.lookupConstructor(constructorName);
   if (constructor != null) {
     constructor = constructor.declaration;
   }
   return constructor;
 }