Ensure that returned cached source have the same actual URI.

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

Index: pkg/analyzer/lib/src/context/source.dart
diff --git a/pkg/analyzer/lib/src/context/source.dart b/pkg/analyzer/lib/src/context/source.dart
index 21cd40e9ba607d06a520a9107de4f3fde18f2f8a..9ea1d7dc8e3a63ae7ad3c94df862a56ed9b27e71 100644
--- a/pkg/analyzer/lib/src/context/source.dart
+++ b/pkg/analyzer/lib/src/context/source.dart
@@ -256,7 +256,7 @@ class SourceFactoryImpl implements SourceFactory {
       }
     }
 
-    return _absoluteUriToSourceCache.putIfAbsent(containedUri, () {
+    return _absoluteUriToSourceCache.putIfAbsent(actualUri, () {
       for (UriResolver resolver in resolvers) {
         Source result = resolver.resolveAbsolute(containedUri, actualUri);
         if (result != null) {