Minor, add regression test for KT-34766

compiler/testData/codegen/box/inlineClasses/whenWithSubject.kt

@@ -0,0 +1,20 @@
+inline class InlineLong(val value: Long)
+inline val Number.toInlineLong get() = InlineLong(this.toLong())
+
+fun box(): String {
+    val value = 0
+
+    val withoutSubject = when (value.toInlineLong) {
+        0.toInlineLong -> true
+        else -> false
+    }
+    if (!withoutSubject) return "Fail: without subject"
+
+    val withSubject = when (val subject = value.toInlineLong) {
+        0.toInlineLong -> true
+        else -> false
+    }
+    if (!withSubject) return "Fail: with subject"
+
+    return "OK"
+}