disable isolate parsing in debug mode (#854)

Co-authored-by: Dan Field <[email protected]>

Author: Jonah Williams

CHANGELOG.md

@@ -2,6 +2,7 @@
 
 ## Next
 
+- Disable Isolate parsing in debug mode.
 - Fix internal Color representation leakage from `package:vector_graphics_compiler`.
 
 ## 2.0.0+1

lib/src/utilities/_compute_io.dart

@@ -2,8 +2,6 @@ import 'dart:async';
 
 import 'package:flutter/foundation.dart' as foundation;
 
-import '_compute_io.dart' if (dart.library.html) '_compute_none.dart';
-
 Future<R> _testCompute<Q, R>(
     foundation.ComputeCallback<Q, R> callback, Q message,
     {String? debugLabel}) {
@@ -14,11 +12,12 @@ Future<R> _testCompute<Q, R>(
   final FutureOr<R> result = callback(message);
   if (result is Future<R>) {
     return result;
-  } else {
-    return foundation.SynchronousFuture<R>(result);
   }
+  return foundation.SynchronousFuture<R>(result);
 }
 
 /// A compute implementation that does not spawn isolates in tests.
-final foundation.ComputeImpl compute =
-    isTest ? _testCompute : foundation.compute;
+const foundation.ComputeImpl compute =
+    (foundation.kDebugMode || foundation.kIsWeb)
+        ? _testCompute
+        : foundation.compute;