[debugger] tuned StepNext and StepOut at return position

test/inspector/debugger/return-break-locations.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.
+
+InspectorTest.log('Return break locations within function');
+
+InspectorTest.addScript(`
+function fib(x) {
+  if (x < 0) return;
+  if (x === 0) return 1;
+  if (x === 1) return fib(0);
+  return x > 2 ? fib(x - 1) + fib(x - 2) : fib(1) + fib(0);
+}
+`);
+
+InspectorTest.runAsyncTestSuite([
+  async function testTailCall() {
+    var scriptPromise = Protocol.Debugger.onceScriptParsed();
+    Protocol.Debugger.enable();
+    var scriptId = (await scriptPromise).params.scriptId;
+    var locations = (await Protocol.Debugger.getPossibleBreakpoints({
+      start: { lineNumber: 0, columnNumber: 0, scriptId }
+    })).result.locations;
+    InspectorTest.logMessage(locations.filter(location => location.type === 'return'));
+  }
+]);