AbstractClosureAnnotator for IR.

compiler/testData/ir/closureAnnotator/topLevelDeclarations.kt

@@ -0,0 +1,10 @@
+fun Int.test1(x: Int) = this + x
+
+class Test2(val x: Int) {
+    fun test3() = x
+    fun Int.test4() = this + x
+}
+
+val test5 = object {
+    fun Int.test6(x: Int) = this + x
+}