KT-244 Use dataflow info while resolving variable initializers

compiler/testData/diagnostics/tests/nullabilityAndAutoCasts/kt244.jet

@@ -0,0 +1,34 @@
+namespace kt244
+
+//+JDK
+
+// KT-244 Use dataflow info while resolving variable initializers
+
+fun f(s: String?) {
+    if (s != null) {
+        s.length  //ok
+        var <!UNUSED_VARIABLE!>i<!> = s.length //error: Only safe calls are allowed on a nullable receiver
+        System.out?.println(s.length) //error
+    }
+}
+
+// more tests
+class A(a: String?) {
+    val b = if (a != null) a.length else 1
+    {
+        if (a != null) {
+            val c = a.length
+        }
+    }
+
+    val i : Int
+
+    {
+        if (a is String) {
+            i = a.length
+        }
+        else {
+            i = 3
+        }
+    }
+}