[parser] improve inferred function names for async arrow functions

test/mjsunit/harmony/async-function-stacktrace.js

 // Copyright 2016 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: --harmony-async-await
 
 async function test(func, funcs) {
   try {
     await func();
     throw new Error("Expected " + func.toString() + " to throw");
@@ skipping 65 matching lines @@
   await test((new class { async c3() {
     await 1;
     try { await thrower(); } catch (e) { throw new Error("FAIL"); }
   } }).c3, ["c3"]);
 
   await test((new class { async c4() {
     await 1;
     try { await reject(); } catch (e) { throw new Error("FAIL"); }
   } }).c4, ["c4"]);
 
-  // TODO(caitp): `async` probably shouldn't be the inferred name for async
-  // arrow functions...
+  // TODO(caitp): We should infer anonymous async functions as the empty
+  // string, not as the name of a function they're passed as a parameter to.
+  await test(async x => { throw new Error("FAIL") },
+             ["test", "test", "runTests"]);
   await test(async() => { throw new Error("FAIL") },
-  ["async", "test", "runTests"]);
+             ["test", "test", "runTests"]);
+  await test(async(a) => { throw new Error("FAIL") },
+             ["test", "test", "runTests"]);
+  await test(async(a, b) => { throw new Error("FAIL") },
+             ["test", "test", "runTests"]);
 
-  await test(async() => { await 1; throw new Error("FAIL") }, ["async"]);
+  await test(async x => { await 1; throw new Error("FAIL") }, ["test"]);
+  await test(async() => { await 1; throw new Error("FAIL") }, ["test"]);
+  await test(async(a) => { await 1; throw new Error("FAIL") }, ["test"]);
+  await test(async(a, b) => { await 1; throw new Error("FAIL") }, ["test"]);
+
+  await test(async x => {
+    await 1;
+    try {
+      await thrower();
+    } catch (e) {
+      throw new Error("FAIL");
+    }
+  }, ["test"]);
 
   await test(async() => {
     await 1;
     try {
       await thrower();
     } catch (e) {
       throw new Error("FAIL");
     }
-  }, ["async"]);
+  }, ["test"]);
+
+  await test(async(a) => {
+    await 1;
+    try {
+      await thrower();
+    } catch (e) {
+      throw new Error("FAIL");
+    }
+  }, ["test"]);
+
+  await test(async(a, b) => {
+    await 1;
+    try {
+      await thrower();
+    } catch (e) {
+      throw new Error("FAIL");
+    }
+  }, ["test"]);
+
+  await test(async x => {
+    await 1;
+    try {
+      await reject();
+    } catch (e) {
+      throw new Error("FAIL");
+    }
+  }, ["test"]);
 
   await test(async() => {
     await 1;
     try {
       await reject();
     } catch (e) {
       throw new Error("FAIL");
     }
-  }, ["async"]);
+  }, ["test"]);
+
+  await test(async(a) => {
+    await 1;
+    try {
+      await reject();
+    } catch (e) {
+      throw new Error("FAIL");
+    }
+  }, ["test"]);
+
+  await test(async(a, b) => {
+    await 1;
+    try {
+      await reject();
+    } catch (e) {
+      throw new Error("FAIL");
+    }
+  }, ["test"]);
 }
 
 runTests().catch(e => {
   print(e);
   quit(1);
 });