var global = require('../internals/global');
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var NativePromiseConstructor = require('../internals/promise-native-constructor');
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var isCallable = require('../internals/is-callable');
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var isForced = require('../internals/is-forced');
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var inspectSource = require('../internals/inspect-source');
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var wellKnownSymbol = require('../internals/well-known-symbol');
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var IS_BROWSER = require('../internals/engine-is-browser');
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var IS_PURE = require('../internals/is-pure');
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var V8_VERSION = require('../internals/engine-v8-version');
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var NativePromisePrototype = NativePromiseConstructor && NativePromiseConstructor.prototype;
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var SPECIES = wellKnownSymbol('species');
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var SUBCLASSING = false;
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var NATIVE_PROMISE_REJECTION_EVENT = isCallable(global.PromiseRejectionEvent);
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var FORCED_PROMISE_CONSTRUCTOR = isForced('Promise', function () {
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var PROMISE_CONSTRUCTOR_SOURCE = inspectSource(NativePromiseConstructor);
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var GLOBAL_CORE_JS_PROMISE = PROMISE_CONSTRUCTOR_SOURCE !== String(NativePromiseConstructor);
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// V8 6.6 (Node 10 and Chrome 66) have a bug with resolving custom thenables
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// https://bugs.chromium.org/p/chromium/issues/detail?id=830565
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// We can't detect it synchronously, so just check versions
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if (!GLOBAL_CORE_JS_PROMISE && V8_VERSION === 66) return true;
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// We need Promise#{ catch, finally } in the pure version for preventing prototype pollution
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if (IS_PURE && !(NativePromisePrototype['catch'] && NativePromisePrototype['finally'])) return true;
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// We can't use @@species feature detection in V8 since it causes
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// deoptimization and performance degradation
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// https://github.com/zloirock/core-js/issues/679
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if (V8_VERSION >= 51 && /native code/.test(PROMISE_CONSTRUCTOR_SOURCE)) return false;
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// Detect correctness of subclassing with @@species support
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var promise = new NativePromiseConstructor(function (resolve) { resolve(1); });
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var FakePromise = function (exec) {
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exec(function () { /* empty */ }, function () { /* empty */ });
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};
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var constructor = promise.constructor = {};
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constructor[SPECIES] = FakePromise;
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SUBCLASSING = promise.then(function () { /* empty */ }) instanceof FakePromise;
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if (!SUBCLASSING) return true;
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// Unhandled rejections tracking support, NodeJS Promise without it fails @@species test
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return !GLOBAL_CORE_JS_PROMISE && IS_BROWSER && !NATIVE_PROMISE_REJECTION_EVENT;
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});
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module.exports = {
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CONSTRUCTOR: FORCED_PROMISE_CONSTRUCTOR,
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REJECTION_EVENT: NATIVE_PROMISE_REJECTION_EVENT,
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SUBCLASSING: SUBCLASSING
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};
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