[cctest] add Async Generator bytecode tests

These were originally written as part of
https://chromium-review.googlesource.com/c/550396/. I've separated them
out into a separate CL with the intent of landing it first, so that it's
easier to see the difference these CLs will have on generated bytecode.

BUG=v8:5855
TBR=tebbi@chromium.org, rmcilroy@chromium.org

Change-Id: Ib84e65847d7396e31b0e38d28f59454cf7c58fc1
Reviewed-on: https://chromium-review.googlesource.com/558221Reviewed-by: Caitlin Potter <caitp@igalia.com>
Commit-Queue: Caitlin Potter <caitp@igalia.com>
Cr-Commit-Position: refs/heads/master@{#46370}

test/cctest/interpreter/test-bytecode-generator.cc

@@ -2358,6 +2358,34 @@ TEST(Generators) {
                      LoadGolden("Generators.golden")));
 }
 
+TEST(AsyncGenerators) {
+  bool old_flag = i::FLAG_harmony_async_iteration;
+  i::FLAG_harmony_async_iteration = true;
+  InitializedIgnitionHandleScope scope;
+  BytecodeExpectationsPrinter printer(CcTest::isolate());
+  printer.set_wrap(false);
+  printer.set_test_function_name("f");
+
+  const char* snippets[] = {
+      "async function* f() { }\n"
+      "f();\n",
+
+      "async function* f() { yield 42 }\n"
+      "f();\n",
+
+      "async function* f() { for (let x of [42]) yield x }\n"
+      "f();\n",
+
+      "function* g() { yield 42 }\n"
+      "async function* f() { yield* g() }\n"
+      "f();\n",
+  };
+
+  CHECK(CompareTexts(BuildActual(printer, snippets),
+                     LoadGolden("AsyncGenerators.golden")));
+  i::FLAG_harmony_async_iteration = old_flag;
+}
+
 TEST(Modules) {
   InitializedIgnitionHandleScope scope;
   BytecodeExpectationsPrinter printer(CcTest::isolate());