Remove last uses of InterfaceImpl<> in Sky C++ code

sky/tools/tester/test_harness_impl.cc

Index: sky/tools/tester/test_harness_impl.cc
diff --git a/sky/tools/tester/test_harness_impl.cc b/sky/tools/tester/test_harness_impl.cc
index 882aff34f212d06b4cfd5dd23057a1e808580ac2..1ece58c17833178dcb1b968646f610dea64668f7 100644
--- a/sky/tools/tester/test_harness_impl.cc
+++ b/sky/tools/tester/test_harness_impl.cc
@@ -9,8 +9,9 @@
 namespace sky {
 namespace tester {
 
-TestHarnessImpl::TestHarnessImpl(TestRunner* test_runner)
-    : test_runner_(test_runner->GetWeakPtr()) {
+TestHarnessImpl::TestHarnessImpl(TestRunner* test_runner,
+                                 mojo::InterfaceRequest<TestHarness> request)
+    : binding_(this, request.Pass()), test_runner_(test_runner->GetWeakPtr()) {
   // FIXME: This is technically when the V8 context gets created and
   // not when the test is started. An error before we instantiated
   // the V8 context would show up before the #BEGIN line for this test.