DDC: mostly incremental compilation, fixes #223

lib/runtime/dart/convert.txt

Index: lib/runtime/dart/convert.txt
diff --git a/lib/runtime/dart/convert.txt b/lib/runtime/dart/convert.txt
new file mode 100644
index 0000000000000000000000000000000000000000..9ff722ac6730ac35693d94b637839484e714ce0d
--- /dev/null
+++ b/lib/runtime/dart/convert.txt
@@ -0,0 +1,14 @@
+warning: [DownCastComposite] result (List<dynamic>) will need runtime check to cast to type List<int> (dart:convert/ascii.dart, line 96, col 12)
+warning: [DownCastComposite] _first.encoder.fuse(_second.encoder) (Converter<S, dynamic>) will need runtime check to cast to type Converter<S, T> (dart:convert/codec.dart, line 87, col 34)
+warning: [DownCastComposite] _second.decoder.fuse(_first.decoder) (Converter<T, dynamic>) will need runtime check to cast to type Converter<T, S> (dart:convert/codec.dart, line 88, col 34)
+warning: [DownCastComposite] JS('JSExtendableArray', '#', keys) (dynamic) will need runtime check to cast to type List<String> (dart:convert, line 311, col 12)
+warning: [DownCastComposite] _second.convert(_first.convert(input)) (dynamic) will need runtime check to cast to type T (dart:convert/converter.dart, line 58, col 25)
+warning: [DownCastComposite] toEncodable ((dynamic) → dynamic) will need runtime check to cast to type (Object) → Object (dart:convert/json.dart, line 142, col 28)
+warning: [DownCastComposite] _toEncodable ((dynamic) → dynamic) will need runtime check to cast to type (Object) → Object (dart:convert/json.dart, line 147, col 28)
+warning: [DownCastComposite] _toEncodable (Function) will need runtime check to cast to type (Object) → dynamic (dart:convert/json.dart, line 270, col 42)
+warning: [DownCastComposite] _toEncodable (Function) will need runtime check to cast to type (Object) → dynamic (dart:convert/json.dart, line 352, col 36)
+warning: [DownCastComposite] _toEncodable (Function) will need runtime check to cast to type (Object) → dynamic (dart:convert/json.dart, line 455, col 53)
+warning: [DownCastComposite] object (dynamic) will need runtime check to cast to type Map<String, Object> (dart:convert/json.dart, line 715, col 16)
+warning: [DownCastComposite] _toEncodable (dynamic) will need runtime check to cast to type (Object) → Object (dart:convert/json.dart, line 817, col 60)
+warning: [DownCastComposite] toEncodable (dynamic) will need runtime check to cast to type (Object) → Object (dart:convert/json.dart, line 895, col 15)
+warning: [DownCastComposite] sink (Sink<dynamic>) will need runtime check to cast to type Sink<String> (dart:convert/line_splitter.dart, line 24, col 44)