fix #27408, reverts "ignore dynamic in inference"

pkg/dev_compiler/tool/sdk_expected_errors.txt

Index: pkg/dev_compiler/tool/sdk_expected_errors.txt
diff --git a/pkg/dev_compiler/tool/sdk_expected_errors.txt b/pkg/dev_compiler/tool/sdk_expected_errors.txt
index 510d108823c01068eeb20ccad62c47bf65983fc2..a7b684df1b69626181c5ccccb446c759aa01b441 100644
--- a/pkg/dev_compiler/tool/sdk_expected_errors.txt
+++ b/pkg/dev_compiler/tool/sdk_expected_errors.txt
@@ -5,7 +5,6 @@
 [error] Invalid override. The type of ChunkedConverter.bind ((dynamic) → dynamic) is not a subtype of Converter<S, T>.bind ((Stream<S>) → Stream<T>). (dart:convert/chunked_conversion.dart, line 14, col 3)
 [error] Invalid override. The type of ChunkedConverter.bind ((dynamic) → dynamic) is not a subtype of StreamTransformer<S, T>.bind ((Stream<S>) → Stream<T>). (dart:convert/chunked_conversion.dart, line 14, col 3)
 [error] Invalid override. The type of ChunkedConverter.startChunkedConversion ((dynamic) → dynamic) is not a subtype of Converter<S, T>.startChunkedConversion ((Sink<T>) → Sink<S>). (dart:convert/chunked_conversion.dart, line 15, col 3)
-[error] The argument type '(dynamic, String) → dynamic' cannot be assigned to the parameter type '(StringBuffer, String) → StringBuffer'. (dart:convert/encoding.dart, line 19, col 33)
 [error] Invalid override. The type of FileList.[]= ((int, File) → void) is not a subtype of JSMutableIndexable.[]= ((int, dynamic) → dynamic). (dart:html, line 16868, col 3)
 [error] Invalid override. The type of HtmlCollection.[]= ((int, Node) → void) is not a subtype of JSMutableIndexable.[]= ((int, dynamic) → dynamic). (dart:html, line 18903, col 3)
 [error] Invalid override. The type of MimeTypeArray.[]= ((int, MimeType) → void) is not a subtype of JSMutableIndexable.[]= ((int, dynamic) → dynamic). (dart:html, line 23817, col 3)
@@ -98,7 +97,6 @@
 [warning] Unsound implicit cast from dynamic to Stream<S> (dart:convert/chunked_conversion.dart, line 14, col 45)
 [warning] Unsound implicit cast from dynamic to Sink<T> (dart:convert/chunked_conversion.dart, line 16, col 36)
 [warning] Unsound implicit cast from dynamic to List<String> (dart:convert, line 311, col 12)
-[warning] Unsound implicit cast from EventSink<dynamic> to EventSink<T> (dart:convert/converter.dart, line 46, col 65)
 [warning] Unsound implicit cast from dynamic to T (dart:core/expando.dart, line 55, col 12)
 [warning] Unsound implicit cast from dynamic to E (dart:core/list.dart, line 126, col 16)
 [warning] The final variable 'origin' must be initialized (dart:html, line 177, col 3)