Do not optimize == for KClasses in redundant boxing elimination

For primitive wrappers such as java.lang.Integer,
  jlc = java.lang.Integer.class
  jlt = java.lang.Integer.TYPE
  !(ljc.equals(ljt))
However, in Kotlin corresponding KClass instances are equal.

 #KT-17748 Fixed Target versions 1.1.50
 #KT-17879 Fixed Target versions 1.1.50

compiler/testData/codegen/box/boxingOptimization/kt17748.kt

@@ -0,0 +1,17 @@
+// IGNORE_BACKEND: JS, NATIVE
+
+fun box(): String {
+    42.doSwitchInt()
+    "".doSwitchString()
+    return "OK"
+}
+
+inline fun <reified E> E.doSwitchInt(): String = when (E::class) {
+    Int::class -> "success!"
+    else -> throw AssertionError()
+}
+
+inline fun <reified E> E.doSwitchString(): String = when(E::class) {
+    String::class -> "success!"
+    else -> throw AssertionError()
+}