Add type arguments to SyntheticInvocation.

test/wrapper_test.dart

Index: test/wrapper_test.dart
diff --git a/test/wrapper_test.dart b/test/wrapper_test.dart
index df26c874d264693918a4906198cb432b6264b951..9067426ce2fc71178c0af65932987fffd7535e7c 100644
--- a/test/wrapper_test.dart
+++ b/test/wrapper_test.dart
@@ -60,6 +60,9 @@ class SyntheticInvocation implements Invocation {
   final int _type;
   const SyntheticInvocation(this.memberName, this.positionalArguments,
       this.namedArguments, this._type);
+
+  List<Type> get typeArguments => const <Type>[];
+
   bool get isMethod => _type == METHOD;
 
   bool get isGetter => _type == GETTER;