Use package property COROUTINE_SUSPENDED instead of enum entry

For sake of encapsulation: actual property content might be
different from the entry

libraries/stdlib/coroutines/js/src/kotlin/coroutines/SafeContinuationJs.kt

@@ -6,6 +6,7 @@
 package kotlin.coroutines
 
 import kotlin.coroutines.intrinsics.CoroutineSingletons.*
+import kotlin.coroutines.intrinsics.COROUTINE_SUSPENDED
 
 @PublishedApi
 @SinceKotlin("1.3")

libraries/stdlib/coroutines/js/src/kotlin/coroutines/js/internal/CoroutineImpl.kt

@@ -5,7 +5,7 @@
 
 package kotlin.coroutines
 
-import kotlin.coroutines.intrinsics.CoroutineSingletons
+import kotlin.coroutines.intrinsics.COROUTINE_SUSPENDED
 
 @SinceKotlin("1.3")
 @JsName("CoroutineImpl")
@@ -45,7 +45,7 @@ internal abstract class CoroutineImpl(private val resultContinuation: Continuati
 
                 try {
                     val outcome = doResume()
-                    if (outcome === CoroutineSingletons.COROUTINE_SUSPENDED) return
+                    if (outcome === COROUTINE_SUSPENDED) return
                     currentResult = outcome
                     currentException = null
                 } catch (exception: dynamic) { // Catch all exceptions

libraries/stdlib/coroutines/jvm/src/kotlin/coroutines/SafeContinuationJvm.kt

@@ -7,6 +7,7 @@ package kotlin.coroutines
 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater
 import kotlin.*
 import kotlin.coroutines.intrinsics.CoroutineSingletons.*
+import kotlin.coroutines.intrinsics.COROUTINE_SUSPENDED
 
 @PublishedApi
 @SinceKotlin("1.3")

libraries/stdlib/coroutines/jvm/src/kotlin/coroutines/jvm/internal/ContinuationImpl.kt

@@ -7,7 +7,7 @@ package kotlin.coroutines.jvm.internal
 
 import java.io.Serializable
 import kotlin.coroutines.*
-import kotlin.coroutines.intrinsics.CoroutineSingletons
+import kotlin.coroutines.intrinsics.COROUTINE_SUSPENDED
 import kotlin.jvm.internal.FunctionBase
 import kotlin.jvm.internal.Reflection
 
@@ -30,7 +30,7 @@ internal abstract class BaseContinuationImpl(
                 val outcome: SuccessOrFailure<Any?> =
                     try {
                         val outcome = invokeSuspend(param)
-                        if (outcome === CoroutineSingletons.COROUTINE_SUSPENDED) return
+                        if (outcome === COROUTINE_SUSPENDED) return
                         SuccessOrFailure.success(outcome)
                     } catch (exception: Throwable) {
                         SuccessOrFailure.failure(exception)