Adjusts dart2js backend to handle method type arguments.

pkg/compiler/lib/src/compile_time_constants.dart

Index: pkg/compiler/lib/src/compile_time_constants.dart
diff --git a/pkg/compiler/lib/src/compile_time_constants.dart b/pkg/compiler/lib/src/compile_time_constants.dart
index 724e6f669eca41b3b3742ed62d178f622b6ba15a..101d8523f48af97e253b398e87cd0437eb4c4646 100644
--- a/pkg/compiler/lib/src/compile_time_constants.dart
+++ b/pkg/compiler/lib/src/compile_time_constants.dart
@@ -238,9 +238,15 @@ abstract class ConstantCompilerBase implements ConstantCompiler {
         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;