Revert "Encode URIs stored in unlinked summaries to make them Uri.parse() safe."

pkg/analyzer/lib/src/dart/analysis/file_state.dart

Index: pkg/analyzer/lib/src/dart/analysis/file_state.dart
diff --git a/pkg/analyzer/lib/src/dart/analysis/file_state.dart b/pkg/analyzer/lib/src/dart/analysis/file_state.dart
index 50ed70a9cb603d8fa7dfc6ac59aab5e010a5325e..d37576d2bcbd0a28018ba241905929910ce9d93b 100644
--- a/pkg/analyzer/lib/src/dart/analysis/file_state.dart
+++ b/pkg/analyzer/lib/src/dart/analysis/file_state.dart
@@ -493,7 +493,12 @@ class FileState {
    * cannot be parsed, cannot correspond any file, etc.
    */
   FileState _fileForRelativeUri(String relativeUri) {
-    Uri absoluteUri = resolveRelativeUri(uri, Uri.parse(relativeUri));
+    Uri absoluteUri;
+    try {
+      absoluteUri = resolveRelativeUri(uri, Uri.parse(relativeUri));
+    } on FormatException {
+      return null;
+    }
     return _fsState.getFileForUri(absoluteUri);
   }