Remove internal 'checkCompletion' function and replace it with the identical 'ensureActive' extension to reduce code duplication

Author: qwwdfsad

kotlinx-coroutines-core/common/src/Builders.common.kt

@@ -150,7 +150,7 @@ public suspend fun <T> withContext(
         val oldContext = uCont.context
         val newContext = oldContext + context
         // always check for cancellation of new context
-        newContext.checkCompletion()
+        newContext.ensureActive()
         // FAST PATH #1 -- new context is the same as the old one
         if (newContext === oldContext) {
             val coroutine = ScopeCoroutine(newContext, uCont)

kotlinx-coroutines-core/common/src/JobSupport.kt

@@ -541,7 +541,7 @@ public open class JobSupport constructor(active: Boolean) : Job, ChildJob, Paren
 
     public final override suspend fun join() {
         if (!joinInternal()) { // fast-path no wait
-            coroutineContext.checkCompletion()
+            coroutineContext.ensureActive()
             return // do not suspend
         }
         return joinSuspend() // slow-path wait

kotlinx-coroutines-core/common/src/Yield.kt

@@ -29,7 +29,7 @@ import kotlin.coroutines.intrinsics.*
  */
 public suspend fun yield(): Unit = suspendCoroutineUninterceptedOrReturn sc@ { uCont ->
     val context = uCont.context
-    context.checkCompletion()
+    context.ensureActive()
     val cont = uCont.intercepted() as? DispatchedContinuation<Unit> ?: return@sc Unit
     if (cont.dispatcher.isDispatchNeeded(context)) {
         // this is a regular dispatcher -- do simple dispatchYield
@@ -49,8 +49,3 @@ public suspend fun yield(): Unit = suspendCoroutineUninterceptedOrReturn sc@ { u
     }
     COROUTINE_SUSPENDED
 }
-
-internal fun CoroutineContext.checkCompletion() {
-    val job = get(Job)
-    if (job != null && !job.isActive) throw job.getCancellationException()
-}