anchor.diff:    return assetString.substring(0, assetString.length - 1).substring(6);
   }
   
  +String _packagePrefixString =
  +    r'^[^' + (path.separator == '\\' ? r'\\' : '/') + r'|]*\|';
  +RegExp _packagePrefix = new RegExp(_packagePrefixString);
  +
   /// Returns the relative path embedded in the given [fullName], which is
   /// expected to be obtained from `Element.fullName` or some other source
   /// using the same format. This means that the package prefix (for
  
positive.code:     for (String entryPoint in entryPoints) {
        L: {
          for (Asset input in inputs) {
            if (input.id.path.endsWith(entryPoint)) {
              aggregateTransform.logger.info("Registering entry point: $input");
              entryPointMap[entryPoint] = input;
              break L;
  
negative.code:             // transformation of libraries in other packages.
              continue;  // Library in different package: cannot be transformed.
            }
            // Compute `libraryToAssetMap`.
            for (Asset input in inputs) {
              if (_isFileAsset(input)) {
                if (_assetPath(input).endsWith(_posixNormalizePath(targetPath))) {
                  // NB: This test would yield an incorrect result in the
                  // case where multiple paths in the package have a shared
                  // suffix (e.g., we have both '/path/one/ending/like/this'
  