Revert "Package map source factory support" [TBR].

pkg/analyzer/lib/src/generated/utilities_dart.dart

Index: pkg/analyzer/lib/src/generated/utilities_dart.dart
diff --git a/pkg/analyzer/lib/src/generated/utilities_dart.dart b/pkg/analyzer/lib/src/generated/utilities_dart.dart
index d5dc0002a1038ef055c43d32ef80c83ea93a2552..26456a59ef81501bbf892f7022f4294b8838f401 100644
--- a/pkg/analyzer/lib/src/generated/utilities_dart.dart
+++ b/pkg/analyzer/lib/src/generated/utilities_dart.dart
@@ -38,28 +38,3 @@ class ParameterKind extends Enum<ParameterKind> {
   const ParameterKind(String name, int ordinal, this.isOptional)
       : super(name, ordinal);
 }
-
-/**
- * Check whether [uri1] starts with (or 'is prefixed by') [uri2] by checking
- * path segments.
- */
-bool startsWith(Uri uri1, Uri uri2) {
-  List<String> uri1Segments = uri1.pathSegments;
-  List<String> uri2Segments = uri2.pathSegments.toList();
-  
-  // Trim trailing empty segments ('/foo/' => ['foo', ''])
-  if (uri2Segments.last == '') {
-    uri2Segments.removeLast();
-  }
-  
-  if (uri2Segments.length > uri1Segments.length) {
-    return false;
-  }
-
-  for (int i = 0; i < uri2Segments.length; ++i) {
-    if (uri2Segments[i] != uri1Segments[i]) {
-      return false;
-    }
-  }
-  return true;
-}