Fix comparison with 0 on non-JVM platforms

Author: zuevmaxim

kotlinx-coroutines-core/common/src/internal/ThreadContext.common.kt

@@ -53,15 +53,15 @@ private val updateState =
         return state
     }
 
+internal expect fun isZeroCount(countOrElement: Any?): Boolean
+
 // countOrElement is pre-cached in dispatched continuation
 // returns NO_THREAD_ELEMENTS if the contest does not have any ThreadContextElements
 internal fun updateThreadContext(context: CoroutineContext, countOrElement: Any?): Any? {
     @Suppress("NAME_SHADOWING")
     val countOrElement = countOrElement ?: threadContextElements(context)
-    @Suppress("IMPLICIT_BOXING_IN_IDENTITY_EQUALS")
     return when {
-        countOrElement === 0 -> NO_THREAD_ELEMENTS // very fast path when there are no active ThreadContextElements
-        //    ^^^ identity comparison for speed, we know zero always has the same identity
+        isZeroCount(countOrElement) -> NO_THREAD_ELEMENTS // very fast path when there are no active ThreadContextElements
         countOrElement is Int -> {
             // slow path for multiple active ThreadContextElements, allocates ThreadState for multiple old values
             context.fold(ThreadState(context, countOrElement), updateState)

kotlinx-coroutines-core/jsAndWasmShared/src/internal/ThreadContext.kt

@@ -0,0 +1,3 @@
+package kotlinx.coroutines.internal
+
+internal actual fun isZeroCount(countOrElement: Any?): Boolean = countOrElement is Int && countOrElement == 0

kotlinx-coroutines-core/jvm/src/internal/ThreadContext.kt

@@ -3,7 +3,9 @@ package kotlinx.coroutines.internal
 import kotlinx.coroutines.*
 import kotlin.coroutines.*
 
-
+// identity comparison for speed, we know zero always has the same identity
+@Suppress("IMPLICIT_BOXING_IN_IDENTITY_EQUALS", "KotlinConstantConditions")
+internal actual fun isZeroCount(countOrElement: Any?): Boolean = countOrElement === 0
 
 // top-level data class for a nicer out-of-the-box toString representation and class name
 @PublishedApi

kotlinx-coroutines-core/native/src/internal/ThreadContext.kt

@@ -0,0 +1,3 @@
+package kotlinx.coroutines.internal
+
+internal actual fun isZeroCount(countOrElement: Any?): Boolean = countOrElement is Int && countOrElement == 0