Check that add() method is in fact MutableCollection.add()

#KT-18881 Fixed

idea/testData/intentions/loopToCallChain/toCollection/KT18881.kt

@@ -0,0 +1,14 @@
+// WITH_RUNTIME
+// IS_APPLICABLE: false
+// IS_APPLICABLE_2: false
+data class Node(private val data: MutableList<String>) {
+    fun add(word: String) {
+        data.add(word)
+    }
+}
+
+fun foo(node: Node, words: List<String>) {
+    <caret>for (word in words) {
+        node.add(word)
+    }
+}