KT-14209 for loop to stdlib: sum is not recognized if before was check for type

#KT-14209 Fixed

idea/testData/intentions/loopToCallChain/sum/smartCastNotNull.kt.after2

@@ -0,0 +1,9 @@
+// WITH_RUNTIME
+// INTENTION_TEXT: "Replace with 'filterNotNull().sum()'"
+// INTENTION_TEXT_2: "Replace with 'asSequence().filterNotNull().sum()'"
+fun foo(list: List<Int?>){
+    val <caret>result = list
+            .asSequence()
+            .filterNotNull()
+            .sum()
+}