Remove "Iterator.iterator()" intrinsic, add stdlib function

idea/testData/highlighter/deprecated/RangeTo.kt

@@ -2,7 +2,7 @@ class MyClass {
   val i = 1
 }
 
-deprecated("Use A instead") fun MyClass.rangeTo(i: MyClass): IntIterator {
+deprecated("Use A instead") fun MyClass.rangeTo(i: MyClass): Iterable<Int> {
     i.i
     throw Exception()
 }

idea/testData/resolve/references/forLoopIn/inBuiltIns/extension.kt

@@ -3,6 +3,6 @@ fun main(it: Iterator<Any>) {
 }
 
 // MULTIRESOLVE
-// REF: (for Iterator<T> in jet).iterator()
+// REF: (for jet.Iterator<T> in jet).iterator()
 // REF: (in jet.Iterator).hasNext()
 // REF: (in jet.Iterator).next()