[inspector] avoid cloning of async call chains

test/inspector/debugger/set-async-call-stack-depth.js

Index: test/inspector/debugger/set-async-call-stack-depth.js
diff --git a/test/inspector/debugger/set-async-call-stack-depth.js b/test/inspector/debugger/set-async-call-stack-depth.js
new file mode 100644
index 0000000000000000000000000000000000000000..444c10591a32a4ed1f2c7e0f70c3f2fd3cdaf5f2
--- /dev/null
+++ b/test/inspector/debugger/set-async-call-stack-depth.js
@@ -0,0 +1,77 @@
+// 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('Checks that we report not more then maxDepth call chains.');
+
+InspectorTest.addScript(`
+function promisesChain(num) {
+  var p = Promise.resolve();
+  for (var i = 0; i < num - 1; ++i) {
+    p = p.then(() => 42);
+  }
+  return p;
+}
+`);
+
+Protocol.Debugger.enable();
+InspectorTest.runAsyncTestSuite([
+  async function testPaused() {
+    let callback = '() => { debugger; }';
+    startTest({ generated: 8, limit: 16, callback});
+    dumpCaptured((await Protocol.Debugger.oncePaused()).params.asyncStackTrace);
+    await Protocol.Debugger.resume();
+
+    startTest({ generated: 8, limit: 8, callback});
+    dumpCaptured((await Protocol.Debugger.oncePaused()).params.asyncStackTrace);
+    await Protocol.Debugger.resume();
+
+    startTest({ generated: 8, limit: 7, callback});
+    dumpCaptured((await Protocol.Debugger.oncePaused()).params.asyncStackTrace);
+    await Protocol.Debugger.resume();
+
+    startTest({ generated: 8, limit: 0, callback});
+    dumpCaptured((await Protocol.Debugger.oncePaused()).params.asyncStackTrace);
+    await Protocol.Debugger.resume();
+  },
+
+  async function testConsoleTrace() {
+    await Protocol.Runtime.enable();
+    let callback = '() => { console.trace(42); }';
+    startTest({ generated: 8, limit: 16, callback});
+    let msg = await Protocol.Runtime.onceConsoleAPICalled();
+    dumpCaptured(msg.params.stackTrace.parent);
+
+    startTest({ generated: 8, limit: 8, callback});
+    msg = await Protocol.Runtime.onceConsoleAPICalled();
+    dumpCaptured(msg.params.stackTrace.parent);
+
+    startTest({ generated: 8, limit: 7, callback});
+    msg = await Protocol.Runtime.onceConsoleAPICalled();
+    dumpCaptured(msg.params.stackTrace.parent);
+
+    startTest({ generated: 8, limit: 0, callback});
+    msg = await Protocol.Runtime.onceConsoleAPICalled();
+    dumpCaptured(msg.params.stackTrace.parent);
+
+    await Protocol.Runtime.disable();
+  }
+]);
+
+function startTest(params) {
+  InspectorTest.log('Actual call chain length: ' + params.generated);
+  InspectorTest.log('setAsyncCallStackDepth(maxDepth): ' + params.limit);
+
+  Protocol.Debugger.setAsyncCallStackDepth({maxDepth: params.limit});
+  Protocol.Runtime.evaluate({expression:
+      `promisesChain(${params.generated}).then(${params.callback})`});
+}
+
+function dumpCaptured(stack) {
+  let count = 0;
+  while (stack) {
+    ++count;
+    stack = stack.parent;
+  }
+  InspectorTest.log('reported: ' + count + '\n');
+}