Fix infinite sequence being terminated prematurely when being iterated without calling hasNext

#KT-16922 Fixed

libraries/stdlib/test/coroutines/SequenceBuilderTest.kt

@@ -287,4 +287,19 @@ class SequenceBuilderTest {
                 effects.toList()
         )
     }
+
+    @Test
+    fun testInfiniteYieldAll() {
+        val values = buildIterator {
+            while (true) {
+                yieldAll((1..5).map { it })
+            }
+        }
+
+        var sum = 0
+        repeat(10) {
+            sum += values.next() //.also(::println)
+        }
+        assertEquals(30, sum)
+    }
 }