Added test for "Can't navigate to sources of the filter() extension function"

#KT-1681can't reproduce

idea/testData/libraries/library/library.kt

@@ -1,5 +1,7 @@
 package testData.libraries
 
+import java.util.*
+
 trait SimpleTrait {
 }
 
@@ -89,4 +91,6 @@ fun func(a : Int, b : Int) {
 }
 
 fun func() {
-}
+}
+
+inline fun <T> T.filter(predicate: (T)-> Boolean) : T? = this