Revert "Add fast-mode Uri class."

sdk/lib/_internal/js_runtime/lib/core_patch.dart

Index: sdk/lib/_internal/js_runtime/lib/core_patch.dart
diff --git a/sdk/lib/_internal/js_runtime/lib/core_patch.dart b/sdk/lib/_internal/js_runtime/lib/core_patch.dart
index 129ce01afaaf6bf9350435eaf264f0ad998b16c9..90045744a631686caee62863c1b19e5750dde889 100644
--- a/sdk/lib/_internal/js_runtime/lib/core_patch.dart
+++ b/sdk/lib/_internal/js_runtime/lib/core_patch.dart
@@ -587,17 +587,15 @@ class NoSuchMethodError {
 @patch
 class Uri {
   @patch
+  static bool get _isWindows => false;
+
+  @patch
   static Uri get base {
     String uri = Primitives.currentUri();
     if (uri != null) return Uri.parse(uri);
     throw new UnsupportedError("'Uri.base' is not supported");
   }
-}
 
-@patch
-class _Uri {
-  @patch
-  static bool get _isWindows => false;
 
   // Matches a String that _uriEncodes to itself regardless of the kind of
   // component.  This corresponds to [_unreservedTable], i.e. characters that