Rationalize coercions

test/dart_codegen/expect/_internal/iterable.dart

 part of dart._internal;
  abstract class EfficientLength {int get length;
 }
  abstract class ListIterable<E> extends IterableBase<E> implements EfficientLength {int get length;
  E elementAt(int i);
  const ListIterable();
  Iterator<E> get iterator => new ListIterator<E>(this);
  void forEach(void action(E element)) {
 int length = this.length;
  for (int i = 0; i < length; i++) {
@@ skipping 242 matching lines @@
  if (length < 0) length = 0;
  List result = growable ? (new List<E>()..length = length) : new List<E>(length);
  for (int i = 0; i < length; i++) {
 result[i] = _iterable.elementAt(start + i);
  if (_iterable.length < end) throw new ConcurrentModificationError(this);
 }
  return DEVC$RT.cast(result, DEVC$RT.type((List<dynamic> _) {
 }
 ), DEVC$RT.type((List<E> _) {
 }
-), "CastDynamic", """line 310, column 12 of dart:_internal/iterable.dart: """, result is List<E>, false);
+), "CompositeCast", """line 310, column 12 of dart:_internal/iterable.dart: """, result is List<E>, false);
 }
 }
  class ListIterator<E> implements Iterator<E> {final Iterable<E> _iterable;
  final int _length;
  int _index;
  E _current;
  ListIterator(Iterable<E> iterable) : _iterable = iterable, _length = iterable.length, _index = 0;
  E get current => _current;
  bool moveNext() {
 int length = _iterable.length;
@@ skipping 13 matching lines @@
  class MappedIterable<S, T> extends IterableBase<T> {final Iterable<S> _iterable;
  final _Transformation<S, T> _f;
  factory MappedIterable(Iterable iterable, T function(S value)) {
 if (iterable is EfficientLength) {
 return new EfficientLengthMappedIterable<S, T>(iterable, function);
 }
  return new MappedIterable<S, T>._(DEVC$RT.cast(iterable, DEVC$RT.type((Iterable<dynamic> _) {
 }
 ), DEVC$RT.type((Iterable<S> _) {
 }
-), "CastDynamic", """line 357, column 39 of dart:_internal/iterable.dart: """, iterable is Iterable<S>, false), function);
+), "CompositeCast", """line 357, column 39 of dart:_internal/iterable.dart: """, iterable is Iterable<S>, false), function);
 }
  MappedIterable._(this._iterable, T this._f(S element));
  Iterator<T> get iterator => new MappedIterator<S, T>(_iterable.iterator, _f);
  int get length => _iterable.length;
  bool get isEmpty => _iterable.isEmpty;
  T get first => _f(_iterable.first);
  T get last => _f(_iterable.last);
  T get single => _f(_iterable.single);
  T elementAt(int index) => _f(_iterable.elementAt(index));
 }
  class EfficientLengthMappedIterable<S, T> extends MappedIterable<S, T> implements EfficientLength {EfficientLengthMappedIterable(Iterable iterable, T function(S value)) : super._(DEVC$RT.cast(iterable, DEVC$RT.type((Iterable<dynamic> _) {
 }
 ), DEVC$RT.type((Iterable<S> _) {
 }
-), "CastDynamic", """line 378, column 17 of dart:_internal/iterable.dart: """, iterable is Iterable<S>, false), function);
+), "CompositeCast", """line 378, column 17 of dart:_internal/iterable.dart: """, iterable is Iterable<S>, false), function);
 }
  class MappedIterator<S, T> extends Iterator<T> {T _current;
  final Iterator<S> _iterator;
  final _Transformation<S, T> _f;
  MappedIterator(this._iterator, T this._f(S element));
  bool moveNext() {
 if (_iterator.moveNext()) {
 _current = _f(_iterator.current);
  return true;
 }
@@ skipping 40 matching lines @@
  return f == null ? null : c;
 }
 , _f, null, DEVC$RT.type((__t2<S, T> _) {
 }
 ), "Wrap", """line 454, column 76 of dart:_internal/iterable.dart: """, _f is __t2<S, T>));
 }
  class ExpandIterator<S, T> implements Iterator<T> {final Iterator<S> _iterator;
  final _ExpandFunction _f;
  Iterator<T> _currentExpansion = ((__x6) => DEVC$RT.cast(__x6, null, DEVC$RT.type((Iterator<T> _) {
 }
-), "CastExact", """line 463, column 35 of dart:_internal/iterable.dart: """, __x6 is Iterator<T>, false))(const EmptyIterator());
+), "InferableAllocation", """line 463, column 35 of dart:_internal/iterable.dart: """, __x6 is Iterator<T>, false))(const EmptyIterator());
  T _current;
  ExpandIterator(this._iterator, Iterable<T> this._f(S element));
  void _nextExpansion() {
 }
  T get current => _current;
  bool moveNext() {
 if (_currentExpansion == null) return false;
  while (!_currentExpansion.moveNext()) {
 _current = null;
  if (_iterator.moveNext()) {
 _currentExpansion = null;
  _currentExpansion = ((__x7) => DEVC$RT.cast(__x7, DEVC$RT.type((Iterator<dynamic> _) {
 }
 ), DEVC$RT.type((Iterator<T> _) {
 }
-), "CastDynamic", """line 481, column 29 of dart:_internal/iterable.dart: """, __x7 is Iterator<T>, false))(_f(_iterator.current).iterator);
+), "CompositeCast", """line 481, column 29 of dart:_internal/iterable.dart: """, __x7 is Iterator<T>, false))(_f(_iterator.current).iterator);
 }
  else {
 return false;
 }
 }
  _current = _currentExpansion.current;
  return true;
 }
 }
  class TakeIterable<E> extends IterableBase<E> {final Iterable<E> _iterable;
@@ skipping 133 matching lines @@
 if (!_f(_iterator.current)) return true;
 }
 }
  return _iterator.moveNext();
 }
  E get current => _iterator.current;
 }
  class EmptyIterable<E> extends IterableBase<E> implements EfficientLength {const EmptyIterable();
  Iterator<E> get iterator => ((__x16) => DEVC$RT.cast(__x16, null, DEVC$RT.type((Iterator<E> _) {
 }
-), "CastExact", """line 678, column 31 of dart:_internal/iterable.dart: """, __x16 is Iterator<E>, false))(const EmptyIterator());
+), "InferableAllocation", """line 678, column 31 of dart:_internal/iterable.dart: """, __x16 is Iterator<E>, false))(const EmptyIterator());
  void forEach(void action(E element)) {
 }
  bool get isEmpty => true;
  int get length => 0;
  E get first {
 throw IterableElementError.noElement();
 }
  E get last {
 throw IterableElementError.noElement();
 }
@@ skipping 211 matching lines @@
  buffer.write(list[i]);
 }
 }
  return buffer.toString();
 }
  Iterable<T> where(Iterable iterable, bool f(var element)) {
 return new WhereIterable<T>(DEVC$RT.cast(iterable, DEVC$RT.type((Iterable<dynamic> _) {
 }
 ), DEVC$RT.type((Iterable<T> _) {
 }
-), "CastDynamic", """line 961, column 33 of dart:_internal/iterable.dart: """, iterable is Iterable<T>, false), DEVC$RT.wrap((bool f(dynamic __u17)) {
+), "CompositeCast", """line 961, column 33 of dart:_internal/iterable.dart: """, iterable is Iterable<T>, false), DEVC$RT.wrap((bool f(dynamic __u17)) {
 bool c(dynamic x0) => f(x0);
  return f == null ? null : c;
 }
 , f, null, DEVC$RT.type((__t18<T> _) {
 }
 ), "Wrap", """line 961, column 43 of dart:_internal/iterable.dart: """, f is __t18<T>));
 }
  static Iterable map(Iterable iterable, f(var element)) {
 return new MappedIterable(iterable, f);
 }
  static Iterable mapList(List list, f(var element)) {
 return new MappedListIterable(list, f);
 }
  static Iterable expand(Iterable iterable, Iterable f(var element)) {
 return new ExpandIterable(iterable, f);
 }
  Iterable<T> takeList(List list, int n) {
 return new SubListIterable<T>(DEVC$RT.cast(list, DEVC$RT.type((List<dynamic> _) {
 }
 ), DEVC$RT.type((Iterable<T> _) {
 }
-), "CastDynamic", """line 978, column 35 of dart:_internal/iterable.dart: """, list is Iterable<T>, false), 0, n);
+), "CompositeCast", """line 978, column 35 of dart:_internal/iterable.dart: """, list is Iterable<T>, false), 0, n);
 }
  Iterable<T> takeWhile(Iterable iterable, bool test(var value)) {
 return new TakeWhileIterable<T>(DEVC$RT.cast(iterable, DEVC$RT.type((Iterable<dynamic> _) {
 }
 ), DEVC$RT.type((Iterable<T> _) {
 }
-), "CastDynamic", """line 983, column 37 of dart:_internal/iterable.dart: """, iterable is Iterable<T>, false), DEVC$RT.wrap((bool f(dynamic __u20)) {
+), "CompositeCast", """line 983, column 37 of dart:_internal/iterable.dart: """, iterable is Iterable<T>, false), DEVC$RT.wrap((bool f(dynamic __u20)) {
 bool c(dynamic x0) => f(x0);
  return f == null ? null : c;
 }
 , test, null, DEVC$RT.type((__t18<T> _) {
 }
 ), "Wrap", """line 983, column 47 of dart:_internal/iterable.dart: """, test is __t18<T>));
 }
  Iterable<T> skipList(List list, int n) {
 return new SubListIterable<T>(DEVC$RT.cast(list, DEVC$RT.type((List<dynamic> _) {
 }
 ), DEVC$RT.type((Iterable<T> _) {
 }
-), "CastDynamic", """line 988, column 35 of dart:_internal/iterable.dart: """, list is Iterable<T>, false), n, null);
+), "CompositeCast", """line 988, column 35 of dart:_internal/iterable.dart: """, list is Iterable<T>, false), n, null);
 }
  Iterable<T> skipWhile(Iterable iterable, bool test(var value)) {
 return new SkipWhileIterable<T>(DEVC$RT.cast(iterable, DEVC$RT.type((Iterable<dynamic> _) {
 }
 ), DEVC$RT.type((Iterable<T> _) {
 }
-), "CastDynamic", """line 993, column 37 of dart:_internal/iterable.dart: """, iterable is Iterable<T>, false), DEVC$RT.wrap((bool f(dynamic __u21)) {
+), "CompositeCast", """line 993, column 37 of dart:_internal/iterable.dart: """, iterable is Iterable<T>, false), DEVC$RT.wrap((bool f(dynamic __u21)) {
 bool c(dynamic x0) => f(x0);
  return f == null ? null : c;
 }
 , test, null, DEVC$RT.type((__t18<T> _) {
 }
 ), "Wrap", """line 993, column 47 of dart:_internal/iterable.dart: """, test is __t18<T>));
 }
  Iterable<T> reversedList(List list) {
 return new ReversedListIterable<T>(DEVC$RT.cast(list, DEVC$RT.type((List<dynamic> _) {
 }
 ), DEVC$RT.type((Iterable<T> _) {
 }
-), "CastDynamic", """line 997, column 40 of dart:_internal/iterable.dart: """, list is Iterable<T>, false));
+), "CompositeCast", """line 997, column 40 of dart:_internal/iterable.dart: """, list is Iterable<T>, false));
 }
  static void sortList(List list, int compare(a, b)) {
 if (compare == null) compare = Comparable.compare;
  Sort.sort(list, compare);
 }
  static void shuffleList(List list, Random random) {
 if (random == null) random = new Random();
  int length = list.length;
  while (length > 1) {
 int pos = random.nextInt(length);
@@ skipping 12 matching lines @@
 }
  static void _rangeCheck(List list, int start, int end) {
 RangeError.checkValidRange(start, end, list.length);
 }
  Iterable<T> getRangeList(List list, int start, int end) {
 _rangeCheck(list, start, end);
  return new SubListIterable<T>(DEVC$RT.cast(list, DEVC$RT.type((List<dynamic> _) {
 }
 ), DEVC$RT.type((Iterable<T> _) {
 }
-), "CastDynamic", """line 1033, column 35 of dart:_internal/iterable.dart: """, list is Iterable<T>, false), start, end);
+), "CompositeCast", """line 1033, column 35 of dart:_internal/iterable.dart: """, list is Iterable<T>, false), start, end);
 }
  static void setRangeList(List list, int start, int end, Iterable from, int skipCount) {
 _rangeCheck(list, start, end);
  int length = end - start;
  if (length == 0) return; if (skipCount < 0) throw new ArgumentError(skipCount);
  List otherList;
  int otherStart;
  if (from is List) {
 otherList = from;
  otherStart = skipCount;
@@ skipping 55 matching lines @@
 RangeError.checkValueInInterval(index, 0, list.length, "index");
  for (var element in iterable) {
 list[index++] = element;
 }
 }
  Map<int, T> asMapList(List l) {
 return new ListMapView<T>(DEVC$RT.cast(l, DEVC$RT.type((List<dynamic> _) {
 }
 ), DEVC$RT.type((List<T> _) {
 }
-), "CastDynamic", """line 1115, column 31 of dart:_internal/iterable.dart: """, l is List<T>, false));
+), "CompositeCast", """line 1115, column 31 of dart:_internal/iterable.dart: """, l is List<T>, false));
 }
  static bool setContainsAll(Set set, Iterable other) {
 for (var element in other) {
 if (!set.contains(element)) return false;
 }
  return true;
 }
  static Set setIntersection(Set set, Set other, Set result) {
 Set smaller;
  Set larger;
@@ skipping 29 matching lines @@
  abstract class IterableElementError {static StateError noElement() => new StateError("No element");
  static StateError tooMany() => new StateError("Too many elements");
  static StateError tooFew() => new StateError("Too few elements");
 }
  typedef Iterable<T> __t2<S, T>(S __u3);
  typedef Iterable<dynamic> __t4(dynamic __u5);
  typedef bool __t9<E>(E __u10);
  typedef bool __t11(dynamic __u12);
  typedef bool __t14<E>(E __u15);
  typedef bool __t18<T>(T __u19);