unwrap parentheses around range expressions in pattern matching conditions (KT-1742) (thanks to Sergey Mashkov for the suggested fix)

compiler/testData/codegen/regressions/kt1742.kt

@@ -0,0 +1,7 @@
+fun box(): String {
+    val x = 2
+    return when(x) {
+        in (1..3) -> "OK"
+        else -> "fail"
+    }
+}