[IR] Eliminate redundant boxing/unboxing of MFVC after inlining

Signed-off-by: Evgeniy.Zhelenskiy <Evgeniy.Zhelenskiy@jetbrains.com>

#KT-1179

compiler/testData/codegen/box/valueClasses/functionReferences.kt

@@ -3,38 +3,13 @@
 // WITH_COROUTINES
 // TARGET_BACKEND: JVM_IR
 // LANGUAGE: +ValueClasses
+// FIR_IDENTICAL
 
 // FILE: caller.kt
 import kotlin.coroutines.*
 
 fun runSuspend(block: suspend () -> Unit) {
-    val run = RunSuspend()
-    block.startCoroutine(run)
-    run.await()
-}
-
-private class RunSuspend : Continuation<Unit> {
-    override val context: CoroutineContext
-        get() = EmptyCoroutineContext
-
-    var result: Result<Unit>? = null
-
-    override fun resumeWith(result: Result<Unit>) = synchronized(this) {
-        this.result = result
-        @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN") (this as Object).notifyAll()
-    }
-
-    fun await() = synchronized(this) {
-        while (true) {
-            when (val result = this.result) {
-                null -> @Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN") (this as Object).wait()
-                else -> {
-                    result.getOrThrow() // throw up failure
-                    return
-                }
-            }
-        }
-    }
+    block.startCoroutine(Continuation(EmptyCoroutineContext) { it.getOrThrow() })
 }
 
 // FILE: test.kt