[debugger] Add initial skeleton for debug test wrapper

test/debugger/wrapper/enable-disable.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.
+
+let compileCount = 0;
+
+const Debug = new DebugWrapper();
+
+Debug.setListener(function(event, exec_state, event_data, data) {
+  if (event != DebugEvent.AfterCompile) return;
+  compileCount++;
+});
+
+Debug.enable();
+assertTrue(compileCount != 0);
+
+const compileCountAfterEnable = compileCount;
+
+Debug.enable();  // Idempotent.
+assertEquals(compileCountAfterEnable, compileCount);
+
+Debug.disable();
+assertEquals(compileCountAfterEnable, compileCount);
+
+Debug.disable();  // Idempotent.
+assertEquals(compileCountAfterEnable, compileCount);
+
+Debug.enable();  // Re-enabling causes recompilation.
+assertEquals(2 * compileCountAfterEnable, compileCount);