Issue 61165. Drain AnalysisDriverScheduler.events when used by package:build

Bug: #61165
Change-Id: Ifb0e7614414bd881c32e4d858c773b8253675570
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/441825
Reviewed-by: Paul Berry <[email protected]>
Commit-Queue: Konstantin Shcheglov <[email protected]>

Author: scheglov

pkg/analyzer/CHANGELOG.md

@@ -1,5 +1,6 @@
 ## 8.1.0-dev
 * Add `DartObject.constructorInvocation` with the constructor and arguments.
+* Fix draining analysis events when used by `package:build`.
 
 ## 8.0.0
 * Remove deprecated element model V1.

pkg/analyzer/lib/src/clients/build_resolvers/build_resolvers.dart

@@ -57,7 +57,10 @@ AnalysisDriverForPackageBuild createAnalysisDriver({
 
   var logger = PerformanceLog(null);
   byteStore ??= MemoryByteStore();
+
   var scheduler = AnalysisDriverScheduler(logger);
+  scheduler.events.drain<void>().ignore();
+
   var sharedOptions = analysisOptions as AnalysisOptionsImpl;
   var optionsMap = AnalysisOptionsMap.forSharedOptions(sharedOptions);
   var driver = AnalysisDriver(