Stress test for comparing analysis performed in two AnalysisContext instances with different option…

pkg/analyzer/lib/src/context/builder.dart

Index: pkg/analyzer/lib/src/context/builder.dart
diff --git a/pkg/analyzer/lib/src/context/builder.dart b/pkg/analyzer/lib/src/context/builder.dart
index 375535328df656d2b4339d34a4cd7afacd48af35..377e9b1e434f11fd2e01610beba1a9686bbb781e 100644
--- a/pkg/analyzer/lib/src/context/builder.dart
+++ b/pkg/analyzer/lib/src/context/builder.dart
@@ -147,6 +147,9 @@ class ContextBuilder {
     Map<String, List<Folder>> folderMap = new HashMap<String, List<Folder>>();
     packages.asMap().forEach((String packagePath, Uri uri) {
       String path = resourceProvider.pathContext.fromUri(uri);
+      if (path.endsWith(resourceProvider.pathContext.separator)) {
+        path = path.substring(0, path.length - 1);
+      }
       folderMap[packagePath] = [resourceProvider.getFolder(path)];
     });
     return folderMap;
@@ -284,7 +287,7 @@ class ContextBuilder {
           return embedderSdk;
         });
         return dartSdk;
-      } else if (extFilePaths != null) {
+      } else if (extFilePaths != null && extFilePaths.isNotEmpty) {
         //
         // We have an extension file, but no embedder file.
         //