Frontend support for function as expression

compiler/testData/diagnostics/tests/functionAsExpression/ScopeCheck.kt

@@ -0,0 +1,20 @@
+// !DIAGNOSTICS: -UNUSED_VARIABLE
+
+trait B {
+    fun b_fun() {}
+}
+
+fun test(param: String) {
+
+    val local_val = 4
+    val bar = fun B.(fun_param: Int) {
+        param.length()
+        b_fun()
+        val inner_bar = local_val + fun_param
+
+        <!UNRESOLVED_REFERENCE!>bar<!>
+    }
+
+    <!UNRESOLVED_REFERENCE!>inner_bar<!>
+    <!UNRESOLVED_REFERENCE!>fun_param<!>
+}