Revert of [inspector] always include user scripts in the snapshot.

test/inspector/debugger/step-snapshot.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.
-
-// Embed a user function in the snapshot and step through it.
-
-// Flags: --embed 'function c(f, ...args) { return f(...args); }'
-
-InspectorTest.setupScriptMap();
-
-InspectorTest.addScript(`
-function test() {
-  function f(x) {
-    return x * 2;
-  }
-  debugger;
-  c(f, 2);
-}
-//# sourceURL=test.js`);
-
-Protocol.Debugger.onPaused(message => {
-  InspectorTest.log("paused");
-  var frames = message.params.callFrames;
-  InspectorTest.logSourceLocation(frames[0].location);
-  Protocol.Debugger.stepInto();
-})
-
-Protocol.Debugger.enable()
-  .then(() => Protocol.Runtime.evaluate({ expression: 'test()' }))
-  .then(InspectorTest.completeTest);