Use type variables on Typedef correctly.

pkg/front_end/lib/src/fasta/kernel/kernel_type_variable_builder.dart

Index: pkg/front_end/lib/src/fasta/kernel/kernel_type_variable_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_type_variable_builder.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_type_variable_builder.dart
index 55ed848eef30eafc97c2189ba099c98cdb9b606f..e0472a2d03a99db9d70604d592e3849b83180d7d 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_type_variable_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_type_variable_builder.dart
@@ -33,11 +33,11 @@ class KernelTypeVariableBuilder
   DartType buildType(
       LibraryBuilder library, List<KernelTypeBuilder> arguments) {
     if (arguments != null) {
-      return inputError(null, null,
-          "Can't use type arguments with type parameter $parameter");
-    } else {
-      return new TypeParameterType(parameter);
+      library.addWarning(arguments.first.charOffset,

[ahe, 2017/07/05 07:55:24]

This test uses a type variable with arguments and wasn't exercised before:

language/generic_function_typedef2_test/04: Pass -> CompileTimeError

+          "Can't use type arguments with type parameter $parameter",
+          fileUri: fileUri);
     }
+    return new TypeParameterType(parameter);
   }
 
   DartType buildTypesWithBuiltArguments(
@@ -55,6 +55,7 @@ class KernelTypeVariableBuilder
   }
 
   void finish(LibraryBuilder library, KernelClassBuilder object) {
-    parameter.bound = bound?.build(library) ?? object.buildType(library, null);
+    parameter.bound ??=
+        bound?.build(library) ?? object.buildType(library, null);
   }
 }