fixes #27586, prefer context type in generic 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 80eacbc89a5eafc9d985d257198439ef4419a129..bfb1d927d9d0d45cabdc215afd863503f2b12112 100644
--- a/pkg/dev_compiler/tool/sdk_expected_errors.txt
+++ b/pkg/dev_compiler/tool/sdk_expected_errors.txt
@@ -1,5 +1,13 @@
-[error] Couldn't infer type parameter 'T'; '_ControllerEventSinkWrapper<dynamic>' must be of type 'EventSink<T>'. (dart:async/stream.dart, line 1346, col 16)
-[error] The argument type '_ControllerEventSinkWrapper' can't be assigned to the parameter type 'EventSink<T>'. (dart:async/stream.dart, line 1346, col 53)
+[error] Couldn't infer type parameter 'T'.
+
+A type could not be found that satisfies these:
+  Argument 'f'   inferred as '(EventSink<T>) → dynamic'             must be a '(T) → R'.
+  Argument 'arg' inferred as '_ControllerEventSinkWrapper<dynamic>' must be a 'T'.
+
+Consider passing explicit type argument(s) to the generic.
+
+ (dart:async/stream.dart, line 1346, col 16)
+[error] The argument type 'ZoneUnaryCallback(EventSink<T>) → dynamic' can't be assigned to the parameter type '(_ControllerEventSinkWrapper<dynamic>) → dynamic'. (dart:async/stream.dart, line 1346, col 32)
 [error] Invalid override. The type of 'ChunkedConverter.bind' ('(dynamic) → dynamic') isn't 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') isn't 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') isn't a subtype of 'Converter<S, T>.startChunkedConversion' ('(Sink<T>) → Sink<S>'). (dart:convert/chunked_conversion.dart, line 15, col 3)