[async-await] don't eagerly resolve Promise before finally blocks have executed

test/mjsunit/es8/async-function-try-finally.js

Index: test/mjsunit/es8/async-function-try-finally.js
diff --git a/test/mjsunit/es8/async-function-try-finally.js b/test/mjsunit/es8/async-function-try-finally.js
new file mode 100644
index 0000000000000000000000000000000000000000..0e10ff9d2d6a3847a82fa5240a7fd5e3f6df04e0
--- /dev/null
+++ b/test/mjsunit/es8/async-function-try-finally.js
@@ -0,0 +1,177 @@
+// Copyright 2017 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax
+
+function assertThrowsAsync(run, errorType, message) {
+  var actual;
+  var hadValue = false;
+  var hadError = false;
+  var promise = run();
+
+  if (typeof promise !== "object" || typeof promise.then !== "function") {
+    throw new MjsUnitAssertionError(
+        "Expected " + run.toString() +
+        " to return a Promise, but it returned " + PrettyPrint(promise));
+  }
+
+  promise.then(function(value) { hadValue = true; actual = value; },
+               function(error) { hadError = true; actual = error; });
+
+  assertFalse(hadValue || hadError);
+
+  %RunMicrotasks();
+
+  if (!hadError) {
+    throw new MjsUnitAssertionError(
+        "Expected " + run + "() to throw " + errorType.name +
+        ", but did not throw.");
+  }
+  if (!(actual instanceof errorType))
+    throw new MjsUnitAssertionError(
+        "Expected " + run + "() to throw " + errorType.name +
+        ", but threw '" + actual + "'");
+  if (message !== void 0 && actual.message !== message)
+    throw new MjsUnitAssertionError(
+        "Expected " + run + "() to throw '" + message + "', but threw '" +
+        actual.message + "'");
+};
+
+function assertEqualsAsync(expected, run, msg) {
+  var actual;
+  var hadValue = false;
+  var hadError = false;
+  var promise = run();
+
+  if (typeof promise !== "object" || typeof promise.then !== "function") {
+    throw new MjsUnitAssertionError(
+        "Expected " + run.toString() +
+        " to return a Promise, but it returned " + PrettyPrint(promise));
+  }
+
+  promise.then(function(value) { hadValue = true; actual = value; },
+               function(error) { hadError = true; actual = error; });
+
+  assertFalse(hadValue || hadError);
+
+  %RunMicrotasks();
+
+  if (hadError) throw actual;
+
+  assertTrue(
+      hadValue, "Expected '" + run.toString() + "' to produce a value");
+
+  assertEquals(expected, actual, msg);
+};
+
+function resolveLater(value) {
+  return new Promise(function(resolve) {
+    resolve(value);
+  });
+}
+
+function rejectLater(reason) {
+  return new Promise(function(resolve, reject) {
+    reject(reason);
+  });
+}
+
+class MyError extends Error {};
+var AsyncFunction = async function() {}.constructor;
+
+assertEqualsAsync("finally-return (func-expr)", async function() {
+  try {
+    return "early-return (func-expr)";
+  } finally {
+    return "finally-return (func-expr)";
+  }
+});
+
+assertEqualsAsync("finally-return (arrow)", async() => {
+  try {
+    return "early-return (arrow)";
+  } finally {
+    return "finally-return (arrow)";
+  }
+});
+
+assertEqualsAsync("finally-return (eval)", AsyncFunction(`
+  try {
+    return "early-return (eval)";
+  } finally {
+    return "finally-return (eval)";
+  }
+`));
+
+assertEqualsAsync("await-finally-return (func-expr)", async function() {
+  try {
+    return "early-return (func-expr)";
+  } finally {
+    return await resolveLater("await-finally-return (func-expr)");
+  }
+});
+
+assertEqualsAsync("await-finally-return (arrow)", async() => {
+  try {
+    return "early-return (arrow)";
+  } finally {
+    return await resolveLater("await-finally-return (arrow)");
+  }
+});
+
+assertEqualsAsync("await-finally-return (eval)", AsyncFunction(`
+  try {
+    return "early-return (eval)";
+  } finally {
+    return await resolveLater("await-finally-return (eval)");
+  }
+`));
+
+assertThrowsAsync(async function() {
+  try {
+    return "early-return (func-expr)";
+  } finally {
+    throw new MyError("finally-throw (func-expr)");
+  }
+}, MyError, "finally-throw (func-expr)");
+
+assertThrowsAsync(async() => {
+  try {
+    return "early-return (arrow)";
+  } finally {
+    throw new MyError("finally-throw (arrow)");
+  }
+}, MyError, "finally-throw (arrow)");
+
+assertThrowsAsync(AsyncFunction(`
+  try {
+    return "early-return (eval)";
+  } finally {
+    throw new MyError("finally-throw (eval)");
+  }
+`), MyError, "finally-throw (eval)");
+
+assertThrowsAsync(async function() {
+  try {
+    return "early-return (func-expr)";
+  } finally {
+    await rejectLater(new MyError("await-finally-throw (func-expr)"));
+  }
+}, MyError, "await-finally-throw (func-expr)");
+
+assertThrowsAsync(async() => {
+  try {
+    return "early-return (arrow)";
+  } finally {
+    await rejectLater(new MyError("await-finally-throw (arrow)"));
+  }
+}, MyError, "await-finally-throw (arrow)");
+
+assertThrowsAsync(AsyncFunction(`
+  try {
+    return "early-return (eval)";
+  } finally {
+    await rejectLater(new MyError("await-finally-throw (eval)"));
+  }
+`), MyError, "await-finally-throw (eval)");