Revert "Detect when isolate reload is barred and inform the user (#5582)" (#5590)

This reverts commit 09e68c33.

AOT snapshotter is broken at this engine rev.

https://flutter-dashboard.appspot.com/api/get-log?ownerKey=ahNzfmZsdXR0ZXItZGFzaGJvYXJkclgLEglDaGVja2xpc3QiOGZsdXR0ZXIvZmx1dHRlci8wOWU2OGMzM2NjZGIzNTVmZWRkNzVhODcxNmRlMDU1MWM3NzJmMmRlDAsSBFRhc2sYgICAgICAwAgM

bin/cache/engine.version

-b2e592592fa070afebd7c062cad245d152a4d370
+28e9b3bc49a83cf5d7a1da2222c02f0f929b1909

packages/flutter_tools/lib/src/hot.dart

@@ -445,18 +445,9 @@ class HotRunner extends ResidentRunner {
       } else {
         flutterUsage.sendEvent('hot', 'reload');
       }
-    } catch (error, st) {
-      int errorCode = error['code'];
-      if (errorCode == Isolate.kIsolateReloadBarred) {
-        printError('Unable to hot reload app due to an unrecoverable error in '
-                   'the source code. Please address the error and then '
-                   'Use "R" to restart the app.');
-        flutterUsage.sendEvent('hot', 'reload-barred');
-        return false;
-      }
-      String errorMessage = error['message'];
+    } catch (errorMessage, st) {
       reloadStatus.stop(showElapsedTime: true);
-      printError('Hot reload failed:\ncode = $errorCode\nmessage = $errorMessage\n$st');
+      printError('Hot reload failed:\n$errorMessage\n$st');
       return false;
     }
     await _evictDirtyAssets();

packages/flutter_tools/lib/src/vmservice.dart

@@ -749,18 +749,12 @@ class Isolate extends ServiceObjectOwner {
     _upgradeCollection(map, this);
   }
 
-  static final int kIsolateReloadBarred = 1005;
-
   Future<Map<String, dynamic>> reloadSources() async {
     try {
       Map<String, dynamic> response = await invokeRpcRaw('_reloadSources');
       return response;
-    } on rpc.RpcException catch(e) {
-      return new Future<Map<String, dynamic>>.error(<String, dynamic>{
-        'code': e.code,
-        'message': e.message,
-        'data': e.data,
-      });
+    } catch (e) {
+      return new Future<Map<String, dynamic>>.error(e.data['details']);
     }
   }