fix default dispatcher for react native

Fixes Kotlin#2843

kotlinx-coroutines-core/js/src/CoroutineContext.kt

@@ -13,12 +13,6 @@ private const val UNDEFINED = "undefined"
 internal external val process: dynamic
 
 internal actual fun createDefaultDispatcher(): CoroutineDispatcher = when {
-    // Check if we are running under ReactNative. We have to use NodeDispatcher under it.
-    // The problem is that ReactNative has a `window` object with `addEventListener`, but it does not  really work.
-    // For details see https://github.com/Kotlin/kotlinx.coroutines/issues/236
-    // The check for ReactNative is based on https://github.com/facebook/react-native/commit/3c65e62183ce05893be0822da217cb803b121c61
-    jsTypeOf(navigator) != UNDEFINED && navigator != null && navigator.product == "ReactNative" ->
-        NodeDispatcher
     // Check if we are running under jsdom. WindowDispatcher doesn't work under jsdom because it accesses MessageEvent#source.
     // It is not implemented in jsdom, see https://github.com/jsdom/jsdom/blob/master/Changelog.md
     // "It's missing a few semantics, especially around origins, as well as MessageEvent source."
@@ -27,7 +21,7 @@ internal actual fun createDefaultDispatcher(): CoroutineDispatcher = when {
     jsTypeOf(window) != UNDEFINED && window.asDynamic() != null && jsTypeOf(window.asDynamic().addEventListener) != UNDEFINED ->
         window.asCoroutineDispatcher()
     // If process is undefined (e.g. in NativeScript, #1404), use SetTimeout-based dispatcher
-    jsTypeOf(process) == UNDEFINED -> SetTimeoutDispatcher
+    jsTypeOf(process) == UNDEFINED || jsTypeOf(process.nextTick) == UNDEFINED -> SetTimeoutDispatcher
     // Fallback to NodeDispatcher when browser environment is not detected
     else -> NodeDispatcher
 }