Restore the performance of checking for ThreadContextElement

Author: dkhalanskyjb

Diff for: kotlinx-coroutines-core/common/src/internal/ThreadContext.common.kt

@@ -53,7 +53,7 @@ private val updateState =
         return state
     }
 
-internal expect fun isZeroCount(countOrElement: Any?): Boolean
+internal expect inline fun isZeroCount(countOrElement: Any?): Boolean
 
 // countOrElement is pre-cached in dispatched continuation
 // returns NO_THREAD_ELEMENTS if the contest does not have any ThreadContextElements

Diff for: kotlinx-coroutines-core/jsAndWasmShared/src/internal/ThreadContext.kt

@@ -1,3 +1,4 @@
 package kotlinx.coroutines.internal
 
-internal actual fun isZeroCount(countOrElement: Any?): Boolean = countOrElement is Int && countOrElement == 0
+@Suppress("NOTHING_TO_INLINE")
+internal actual inline fun isZeroCount(countOrElement: Any?): Boolean = countOrElement is Int && countOrElement == 0

Diff for: kotlinx-coroutines-core/jvm/src/internal/ThreadContext.kt

@@ -4,8 +4,8 @@ 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
+@Suppress("IMPLICIT_BOXING_IN_IDENTITY_EQUALS", "KotlinConstantConditions", "NOTHING_TO_INLINE")
+internal actual inline fun isZeroCount(countOrElement: Any?): Boolean = countOrElement === 0
 
 // top-level data class for a nicer out-of-the-box toString representation and class name
 @PublishedApi

Diff for: kotlinx-coroutines-core/native/src/internal/ThreadContext.kt

@@ -1,3 +1,4 @@
 package kotlinx.coroutines.internal
 
-internal actual fun isZeroCount(countOrElement: Any?): Boolean = countOrElement is Int && countOrElement == 0
+@Suppress("NOTHING_TO_INLINE")
+internal actual inline fun isZeroCount(countOrElement: Any?): Boolean = countOrElement is Int && countOrElement == 0