added DataFlowInfoTest

compiler/testData/cfg-variables/basic/VariablesInitialization.kt

@@ -0,0 +1,16 @@
+fun foo() {
+    val a = 1
+    val b: Int
+    b = 2
+    42
+}
+
+fun bar(foo: Foo) {
+    foo.c
+    foo.c = 2
+    42
+}
+
+trait Foo {
+    var c: Int
+}