Fix method call type inference with explicit type parameters.

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

Index: pkg/front_end/lib/src/fasta/kernel/body_builder.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
index 4ab3a43f6ad34a8a707ad4d1fd888274d2d61e3f..6b0610f3f82c64fbd829bbe7195b5fc3e415956d 100644
--- a/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/body_builder.dart
@@ -586,7 +586,8 @@ class BodyBuilder extends ScopeListener<JumpTarget> implements BuilderHelper {
     List<DartType> typeArguments = pop();
     Object receiver = pop();
     if (arguments != null && typeArguments != null) {
-      arguments.types.addAll(typeArguments);
+      assert(arguments.types.isEmpty);
+      astFactory.setExplicitArgumentTypes(arguments, typeArguments);
     } else {
       assert(typeArguments == null);
     }