Support `void` as generic argument.

pkg/compiler/lib/src/js_emitter/startup_emitter/emitter.dart

Index: pkg/compiler/lib/src/js_emitter/startup_emitter/emitter.dart
diff --git a/pkg/compiler/lib/src/js_emitter/startup_emitter/emitter.dart b/pkg/compiler/lib/src/js_emitter/startup_emitter/emitter.dart
index 79c1e74da544add270b58166434d35e69e2ee3fe..2a7474f1eff9659b6acc389071f5983a06a9af8e 100644
--- a/pkg/compiler/lib/src/js_emitter/startup_emitter/emitter.dart
+++ b/pkg/compiler/lib/src/js_emitter/startup_emitter/emitter.dart
@@ -165,6 +165,9 @@ class Emitter implements emitterTask.Emitter {
       case JsBuiltin.createFunctionTypeRti:
         return _backend.rtiEncoder.templateForCreateFunctionType;
 
+      case JsBuiltin.isVoidRti:
+        return _backend.rtiEncoder.templateForIsVoidRti;
+
       case JsBuiltin.isSubtype:
         // TODO(floitsch): move this closer to where is-check properties are
         // built.