JS: fix corner case in when translation (fix crash in KT-22544)

compiler/testData/codegen/box/when/switchOptimizationSingleStatementCase.kt

@@ -0,0 +1,27 @@
+// CHECK_CASES_COUNT: function=test1 count=2
+// CHECK_IF_COUNT: function=test1 count=0
+// CHECK_BREAKS_COUNT: function=test1 count=1
+
+// CHECK_CASES_COUNT: function=test2 count=2
+// CHECK_IF_COUNT: function=test2 count=0
+// CHECK_BREAKS_COUNT: function=test2 count=1
+
+fun test1(v: Int) {
+    when (v) {
+        1, 2 -> Unit
+    }
+}
+
+fun test2(v: Int) {
+    loop@ while(true) {
+        when (v) {
+            1, 2 -> break@loop
+        }
+    }
+}
+
+fun box(): String {
+    test1(1)
+    test2(1)
+    return "OK"
+}