Adjusts dart2js backend to handle method type arguments.

pkg/compiler/lib/src/compile_time_constants.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.
 
 library dart2js.compile_time_constant_evaluator;
 
 import 'common.dart';
 import 'common/resolution.dart' show Resolution;
 import 'common/tasks.dart' show CompilerTask;
 import 'compiler.dart' show Compiler;
@@ skipping 220 matching lines @@
       expression = compileNodeWithDefinitions(initializer, definitions,
           isConst: isConst);
       if (compiler.options.enableTypeAssertions &&
           checkType &&
           expression != null &&
           element.isField) {
         DartType elementType = element.type;
         ConstantValue value = getConstantValue(expression);
         if (elementType.isMalformed && !value.isNull) {
           if (isConst) {
-            ErroneousElement element = elementType.element;
-            reporter.reportErrorMessage(
-                node, element.messageKind, element.messageArguments);
+            if (elementType is MalformedType) {

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

Add a TODO for me here; I'm not sure we should generate an error here.

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

Done.

+              ErroneousElement element = elementType.element;
+              reporter.reportErrorMessage(
+                  node, element.messageKind, element.messageArguments);
+            } else {
+              assert(elementType is MethodTypeVariableType);
+              reporter.reportErrorMessage(
+                  node, MessageKind.TYPE_VARIABLE_FROM_METHOD_NOT_REIFIED);
+            }
           } else {
             // We need to throw an exception at runtime.
             expression = null;
           }
         } else {
           DartType constantType = value.getType(coreTypes);
           if (!constantSystem.isSubtype(
               compiler.types, constantType, elementType)) {
             if (isConst) {
               reporter.reportErrorMessage(node, MessageKind.NOT_ASSIGNABLE,
@@ skipping 1088 matching lines @@
 class _CompilerEnvironment implements Environment {
   final Compiler compiler;
 
   _CompilerEnvironment(this.compiler);
 
   @override
   String readFromEnvironment(String name) {
     return compiler.fromEnvironment(name);
   }
 }