Add test for uncovered case.

js/js.translator/testFiles/expression/misc/cases/whenReturnedWithoutBlock.kt

@@ -0,0 +1,18 @@
+package foo
+
+fun box() : Boolean {
+  if (t(1) != 0) {
+      return false
+  }
+  if (t(0) != 1) {
+      return false
+  }
+  return (t(100) == 2)
+
+}
+
+fun t(i : Int) = when(i) {
+  0 -> 1
+  1 -> 0
+  else -> 2
+}