[debug] add exception predictions to builtins where missing.

test/debugger/debug/es8/async-debug-builtin-predictions.js

+// 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.
+
+Debug = debug.Debug
+
+var exception = null;
+
+function listener(event, exec_state, event_data, data) {
+  if (event != Debug.DebugEvent.Exception) return;
+  try {
+    var line = exec_state.frame(0).sourceLineText();
+    var match = /Exception/.exec(line);
+    assertNotNull(match);
+  } catch (e) {
+    exception = e;
+  }
+}
+
+// Caught throw, events on any exception.
+Debug.setListener(listener);
+Debug.setBreakOnException();
+
+var thenable = {
+  get then() {
+    throw new Error();  // Exception
+  }
+};
+
+var p = Promise.resolve(thenable);
+
+async function foo() {
+  await thenable;
+}
+
+foo();
+
+%RunMicrotasks();
+
+Debug.setListener(null);
+Debug.clearBreakOnException();
+assertNull(exception);