Fix conversion of assignment as expression in J2K

Blockless if's and so with assignment as expression inside
should turn into blockful
 #KT-16816 fixed

j2k/testData/fileOrElement/ifStatement/assignmentAsExpressionInIf.kt

@@ -0,0 +1,14 @@
+class SomeClass {
+    internal fun doSomeIf(i: Int) {
+        val a: Int
+        val b: Int
+        val c: Int
+        if (i < 0) {
+            b = i
+            a = b
+        } else {
+            c = i
+            b = c
+        }
+    }
+}