Support trailing comma

^KT-34743 Fixed

compiler/testData/diagnostics/testsWithStdLib/trailingComma/whenEntryWithDisabledFeature.kt

@@ -0,0 +1,49 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE, -UNUSED_EXPRESSION -NAME_SHADOWING
+
+fun foo1(x: Any) = when (x) {
+    Comparable::class,
+    Iterable::class,
+    String::class<!UNSUPPORTED_FEATURE!>,<!>
+        -> println(1)
+    else -> println(3)
+}
+
+fun foo2(x: Any) {
+    val z = when (val y: Int = x as Int) {
+        1<!UNSUPPORTED_FEATURE!>,<!> -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo3(x: (Any) -> Any) {
+    val z = when (val y: (Any) -> Any = x) {
+        {x: Any<!UNSUPPORTED_FEATURE!>,<!> -> x}, {y: Any<!UNSUPPORTED_FEATURE!>,<!> -> y}<!UNSUPPORTED_FEATURE!>,<!> -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo4(x: Any) {
+    val z = when (x) {
+        is Int, is Double<!UNSUPPORTED_FEATURE!>,<!> -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo5(x: Int, y: IntArray, z: IntArray) {
+    val u = when (x) {
+        in y,
+        in z<!UNSUPPORTED_FEATURE!>,<!>
+            -> println(1)
+        else -> println(3)
+    }
+}
+
+fun foo6(x: Boolean?) = when (x) {
+    true, false<!UNSUPPORTED_FEATURE!>,<!> -> println(1)
+    null<!UNSUPPORTED_FEATURE!>,<!> -> println(1)
+}
+
+fun foo7(x: Boolean?) = when (x) {
+    true, false<!UNSUPPORTED_FEATURE!>,<!>/**/ -> println(1)
+    null<!UNSUPPORTED_FEATURE!>,<!>/**/ -> println(1)
+}