[cfe] Run ErrorCommentCheck last

This allows seeing the generated AST before failing on error comment discrepancies.

Change-Id: I9d43c37a9b5922818c58928056c194867d378056
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/408521
Reviewed-by: Jens Johansen <[email protected]>
Commit-Queue: Johnni Winther <[email protected]>

Author: johnniwinther

pkg/front_end/test/testing/suite.dart

@@ -269,11 +269,11 @@ class FastaContext extends ChainContext with MatchContext {
       this.soundNullSafety)
       : steps = <Step>[
           new Outline(compileMode, updateComments: updateComments),
-          new ErrorCommentChecker(compileMode),
           const Print(),
           new Verify(compileMode == CompileMode.full
               ? VerificationStage.afterConstantEvaluation
-              : VerificationStage.outline)
+              : VerificationStage.outline),
+          new ErrorCommentChecker(compileMode),
         ],
         suiteFolderOptions = new SuiteFolderOptions(baseUri),
         suiteTestOptions = new SuiteTestOptions() {