[benchmarks] Remove unnecessary utf8.encode() as Uint8List downcast

The return type of `utf8.encode()` was made more precise in [0] (from
`List<int>` to `Uint8List`)

[0] https://dart-review.googlesource.com/c/sdk/+/254903

TEST=ci

Change-Id: I3e578ac8dc5f3f66396cb374e3dcadd989919518
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/321860
Commit-Queue: Martin Kustermann <[email protected]>
Reviewed-by: Daco Harkes <[email protected]>

Author: mkustermann

benchmarks/IsolateJson/dart/IsolateJson.dart

@@ -42,7 +42,7 @@ Uint8List createSampleJson(final size) {
   for (int i = 0; i < size; i++) {
     map['$i'] = list;
   }
-  return utf8.encode(json.encode(map)) as Uint8List;
+  return utf8.encode(json.encode(map));
 }
 
 class JsonDecodeRequest {
@@ -113,22 +113,19 @@ class BenchmarkConfig {
 Future<void> main() async {
   final jsonString =
       File('benchmarks/IsolateJson/dart/sample.json').readAsStringSync();
-  final json250KB = utf8.encode(jsonString) as Uint8List; // 294356 bytes
+  final json250KB = utf8.encode(jsonString); // 294356 bytes
   final decoded = json.decode(utf8.decode(json250KB));
   final decoded1MB = <dynamic, dynamic>{
     '1': decoded['1'],
     '2': decoded['1'],
     '3': decoded['1'],
     '4': decoded['1'],
   };
-  final json1MB =
-      utf8.encode(json.encode(decoded1MB)) as Uint8List; // 1177397 bytes
+  final json1MB = utf8.encode(json.encode(decoded1MB)); // 1177397 bytes
   decoded['1'] = (decoded['1'] as List).sublist(0, 200);
-  final json100KB =
-      utf8.encode(json.encode(decoded)) as Uint8List; // 104685 bytes
+  final json100KB = utf8.encode(json.encode(decoded)); // 104685 bytes
   decoded['1'] = (decoded['1'] as List).sublist(0, 100);
-  final json50KB =
-      utf8.encode(json.encode(decoded)) as Uint8List; // 51760 bytes
+  final json50KB = utf8.encode(json.encode(decoded)); // 51760 bytes
 
   final configs = <BenchmarkConfig>[
     BenchmarkConfig('50KB', json50KB),

benchmarks/Utf8Decode/dart/Utf8Decode.dart

@@ -39,7 +39,7 @@ class Utf8Decode extends BenchmarkBase {
 
   @override
   void setup() {
-    final Uint8List data = utf8.encode(text) as Uint8List;
+    final Uint8List data = utf8.encode(text);
     if (data.length != 10000) {
       throw 'Expected input data of exactly 10000 bytes.';
     }

benchmarks/Utf8Decode/dart2/Utf8Decode.dart

@@ -41,7 +41,7 @@ class Utf8Decode extends BenchmarkBase {
 
   @override
   void setup() {
-    final Uint8List data = utf8.encode(text) as Uint8List;
+    final Uint8List data = utf8.encode(text);
     if (data.length != 10000) {
       throw 'Expected input data of exactly 10000 bytes.';
     }