[modular tests] Cleanup while reading the code.

* Use NewRequest() rather than assignment to connect environment
  services. This saves on explicit template parameters.

* Coherently build puppet master requests bottom-up.

TESTED=built, ran session_shell test.

Change-Id: I07388e9f220e0c95fad61393e4829d15f5a46a52
diff --git a/tests/session_shell/session_shell_test_session_shell.cc b/tests/session_shell/session_shell_test_session_shell.cc
index d6a9fae..5b4cb8d 100644
--- a/tests/session_shell/session_shell_test_session_shell.cc
+++ b/tests/session_shell/session_shell_test_session_shell.cc
@@ -140,11 +140,9 @@
       : ComponentBase(startup_context) {
     TestInit(__FILE__);
 
-    session_shell_context_ = startup_context->ConnectToEnvironmentService<
-        fuchsia::modular::SessionShellContext>();
-    puppet_master_ =
-        startup_context
-            ->ConnectToEnvironmentService<fuchsia::modular::PuppetMaster>();
+    startup_context->ConnectToEnvironmentService(
+        session_shell_context_.NewRequest());
+    startup_context->ConnectToEnvironmentService(puppet_master_.NewRequest());
 
     session_shell_context_->GetStoryProvider(story_provider_.NewRequest());
     story_provider_state_watcher_.Watch(&story_provider_);
@@ -223,7 +221,6 @@
     const std::string initial_json = R"({"created-with-info": true})";
     puppet_master_->ControlStory("story1", story_puppet_master_.NewRequest());
 
-    fidl::VectorPtr<fuchsia::modular::StoryCommand> commands;
     fuchsia::modular::AddMod add_mod;
     add_mod.mod_name.push_back("mod1");
     add_mod.intent.handler = kCommonActiveModule;
@@ -237,6 +234,8 @@
 
     fuchsia::modular::StoryCommand command;
     command.set_add_mod(std::move(add_mod));
+
+    fidl::VectorPtr<fuchsia::modular::StoryCommand> commands;
     commands.push_back(std::move(command));
 
     story_puppet_master_->Enqueue(std::move(commands));
@@ -285,13 +284,14 @@
   void TestStory2() {
     puppet_master_->ControlStory("story2", story_puppet_master_.NewRequest());
 
-    fidl::VectorPtr<fuchsia::modular::StoryCommand> commands;
     fuchsia::modular::AddMod add_mod;
     add_mod.mod_name.push_back("mod1");
     add_mod.intent.handler = kCommonNullModule;
 
     fuchsia::modular::StoryCommand command;
     command.set_add_mod(std::move(add_mod));
+
+    fidl::VectorPtr<fuchsia::modular::StoryCommand> commands;
     commands.push_back(std::move(command));
 
     story_puppet_master_->Enqueue(std::move(commands));
@@ -387,6 +387,7 @@
     fuchsia::modular::StoryOptions story_options;
     story_options.kind_of_proto_story = true;
     story_puppet_master_->SetCreateOptions(std::move(story_options));
+
     story_puppet_master_->Execute(
         [this](fuchsia::modular::ExecuteResult result) {
           story_provider_state_watcher_.SetKindOfProtoStory("story3");