partial fix for #414, avoid dcall in _convertToDart

test/codegen/expect/collection/wrappers.txt

Index: test/codegen/expect/collection/wrappers.txt
diff --git a/test/codegen/expect/collection/wrappers.txt b/test/codegen/expect/collection/wrappers.txt
index dd3439aec59c68dc63c281ee8e864c4f8476b494..56eb8f0994bf6f43b3861759905e5ef7427760fb 100644
--- a/test/codegen/expect/collection/wrappers.txt
+++ b/test/codegen/expect/collection/wrappers.txt
@@ -1,17 +1,17 @@
 // Messages from compiling wrappers.dart
 severe: [INVALID_METHOD_OVERRIDE] Invalid override. The type of _DelegatingIterableBase.expand (((E) → Iterable<dynamic>) → Iterable<dynamic>) is not a subtype of Iterable<E>.expand (<T>((E) → Iterable<T>) → Iterable<T>). (package:collection/wrappers.dart, line 41, col 3)
 severe: [INVALID_METHOD_OVERRIDE] Invalid override. The type of _DelegatingIterableBase.map (((E) → dynamic) → Iterable<dynamic>) is not a subtype of Iterable<E>.map (<T>((E) → T) → Iterable<T>). (package:collection/wrappers.dart, line 68, col 3)
-severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.expand' and 'Iterable.map' (package:collection/wrappers.dart, line 117, col 7)
+severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.map' and 'Iterable.expand' (package:collection/wrappers.dart, line 117, col 7)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.expand (((E) → Iterable<dynamic>) → Iterable<dynamic>) is not a subtype of Iterable<E>.expand (<T>((E) → Iterable<T>) → Iterable<T>). (package:collection/wrappers.dart, line 117, col 25)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.map (((E) → dynamic) → Iterable<dynamic>) is not a subtype of Iterable<E>.map (<T>((E) → T) → Iterable<T>). (package:collection/wrappers.dart, line 117, col 25)
 severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.map' and 'Iterable.expand' (package:collection/wrappers.dart, line 216, col 7)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.expand (((E) → Iterable<dynamic>) → Iterable<dynamic>) is not a subtype of Iterable<E>.expand (<T>((E) → Iterable<T>) → Iterable<T>). (package:collection/wrappers.dart, line 216, col 24)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.map (((E) → dynamic) → Iterable<dynamic>) is not a subtype of Iterable<E>.map (<T>((E) → T) → Iterable<T>). (package:collection/wrappers.dart, line 216, col 24)
-severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.expand' and 'Iterable.map' (package:collection/wrappers.dart, line 269, col 7)
+severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.map' and 'Iterable.expand' (package:collection/wrappers.dart, line 269, col 7)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.expand (((E) → Iterable<dynamic>) → Iterable<dynamic>) is not a subtype of Iterable<E>.expand (<T>((E) → Iterable<T>) → Iterable<T>). (package:collection/wrappers.dart, line 269, col 26)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.map (((E) → dynamic) → Iterable<dynamic>) is not a subtype of Iterable<E>.map (<T>((E) → T) → Iterable<T>). (package:collection/wrappers.dart, line 269, col 26)
 severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.expand' and 'Iterable.map' (package:collection/wrappers.dart, line 367, col 7)
-severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.expand' and 'Iterable.map' (package:collection/wrappers.dart, line 452, col 7)
+severe: [AnalyzerMessage] Missing concrete implementation of 'Iterable.map' and 'Iterable.expand' (package:collection/wrappers.dart, line 452, col 7)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.expand (((V) → Iterable<dynamic>) → Iterable<dynamic>) is not a subtype of Iterable<V>.expand (<T>((V) → Iterable<T>) → Iterable<T>). (package:collection/wrappers.dart, line 452, col 25)
 severe: [INVALID_METHOD_OVERRIDE] Base class introduces an invalid override. The type of _DelegatingIterableBase.map (((V) → dynamic) → Iterable<dynamic>) is not a subtype of Iterable<V>.map (<T>((V) → T) → Iterable<T>). (package:collection/wrappers.dart, line 452, col 25)
 warning: [DOWN_CAST_COMPOSITE] _base.fold(initialValue, combine) (dynamic) will need runtime check to cast to type T (package:collection/wrappers.dart, line 49, col 7)