Server custom error severity support (#24452).

pkg/analysis_server/lib/src/domain_analysis.dart

Index: pkg/analysis_server/lib/src/domain_analysis.dart
diff --git a/pkg/analysis_server/lib/src/domain_analysis.dart b/pkg/analysis_server/lib/src/domain_analysis.dart
index bd9d6073a4e1fdbb47b08b8265047cec6c4721e8..19cf98e184bbe8d4fbfd4651cf16e44883d3aeff 100644
--- a/pkg/analysis_server/lib/src/domain_analysis.dart
+++ b/pkg/analysis_server/lib/src/domain_analysis.dart
@@ -65,7 +65,8 @@ class AnalysisDomainHandler implements RequestHandler {
           if (errorInfo == null) {
             server.sendResponse(new Response.getErrorsInvalidFile(request));
           } else {
-            errors = doAnalysisError_listFromEngine(
+            engine.AnalysisContext context = server.getAnalysisContext(file);
+            errors = doAnalysisError_listFromEngine(context,
                 errorInfo.lineInfo, errorInfo.errors);
             server.sendResponse(
                 new AnalysisGetErrorsResult(errors).toResponse(request.id));