KT-4405 Control-flow analysis is not performed for some local declarations #KT-4405 Fixed

compiler/testData/diagnostics/tests/backingField/ReadInAnonymous.kt

@@ -1,6 +1,6 @@
 class ReadByAnotherPropertyInitializer() {
     val a = 1
     {
-        val x = $a
+        val <!UNUSED_VARIABLE!>x<!> = $a
     }
 }