Fix computation of single type variables.

pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart

Index: pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart b/pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart
index 7cd47ff6829f3bbcb9af4982b0bcbc5f04a757ea..bce17e8db76ab7b7b4ae990d07be105057cc52f4 100644
--- a/pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/old_emitter/class_emitter.dart
@@ -609,7 +609,7 @@ class ClassEmitter extends CodeEmitterHelper {
             cls, element.typeDeclaration, alwaysGenerateFunction: true);
     if (substitution != null) {
       computeTypeVariable =
-          js(r'#(this.$builtinTypeInfo)',
+          js(r'#.apply(null, this.$builtinTypeInfo)',
              substitution.getCodeForVariable(index, backend.rti));
     } else {
       // TODO(ahe): These can be generated dynamically.