Add our own primitive boxing methods to stdlib

These methods are very thin wrappers around primitive wrapper classes
constructors.
They are used by coroutines code which returns primitives and this way
HotSpot is able to throw the allocations away completely.
 #KT-26591 Fixed

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

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2010-2018 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license
+ * that can be found in the license/LICENSE.txt file.
+ */
+
+@file:JvmName("Boxing")
+
+@file:Suppress("PLATFORM_CLASS_MAPPED_TO_KOTLIN")
+
+package kotlin.coroutines.jvm.internal
+
+/*
+ * Box primitive to Java wrapper class by allocating the wrapper object.
+ *
+ * This allows HotSpot JIT to eliminate allocations completely in coroutines code with primitives.
+ */
+
+@SinceKotlin("1.3")
+@PublishedApi
+internal fun boxBoolean(primitive: Boolean): java.lang.Boolean = java.lang.Boolean.valueOf(primitive) as java.lang.Boolean
+
+@SinceKotlin("1.3")
+@PublishedApi
+internal fun boxByte(primitive: Byte): java.lang.Byte = java.lang.Byte.valueOf(primitive) as java.lang.Byte
+
+@SinceKotlin("1.3")
+@PublishedApi
+internal fun boxShort(primitive: Short): java.lang.Short = java.lang.Short(primitive)
+
+@SinceKotlin("1.3")
+@PublishedApi
+internal fun boxInt(primitive: Int): java.lang.Integer = java.lang.Integer(primitive)
+
+@SinceKotlin("1.3")
+@PublishedApi
+internal fun boxLong(primitive: Long): java.lang.Long = java.lang.Long(primitive)
+
+@SinceKotlin("1.3")
+@PublishedApi
+internal fun boxFloat(primitive: Float): java.lang.Float = java.lang.Float(primitive)
+
+@SinceKotlin("1.3")
+@PublishedApi
+internal fun boxDouble(primitive: Double): java.lang.Double = java.lang.Double(primitive)
+
+@SinceKotlin("1.3")
+@PublishedApi
+internal fun boxChar(primitive: Char): java.lang.Character = java.lang.Character(primitive)