Clean size/length/first/head/empty properties and functions.

libraries/stdlib/test/collections/IterableTests.kt

@@ -107,7 +107,7 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
         val foo = data.filter { it.startsWith("f") }
         expect(true) { foo is List<String> }
         expect(true) { foo.all { it.startsWith("f") } }
-        expect(1) { foo.size }
+        expect(1) { foo.size() }
         assertEquals(listOf("foo"), foo)
     }
 
@@ -115,7 +115,7 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
         val notFoo = data.filterNot { it.startsWith("f") }
         expect(true) { notFoo is List<String> }
         expect(true) { notFoo.none { it.startsWith("f") } }
-        expect(1) { notFoo.size }
+        expect(1) { notFoo.size() }
         assertEquals(listOf("bar"), notFoo)
     }
 
@@ -159,7 +159,7 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
         assertTrue {
             lengths.all { it == 3 }
         }
-        assertEquals(2, lengths.size)
+        assertEquals(2, lengths.size())
         assertEquals(arrayListOf(3, 3), lengths)
     }
 
@@ -220,7 +220,7 @@ abstract class IterableTests<T : Iterable<String>>(val data: T, val empty: T) {
     Test
     fun reduce() {
         val reduced = data.reduce {a, b -> a + b }
-        assertEquals(6, reduced.size)
+        assertEquals(6, reduced.length())
         assertTrue(reduced == "foobar" || reduced == "barfoo")
     }
 }