Revert "dart2js: add compiler builtins to the core-runtime."

pkg/compiler/lib/src/js_backend/backend.dart

Index: pkg/compiler/lib/src/js_backend/backend.dart
diff --git a/pkg/compiler/lib/src/js_backend/backend.dart b/pkg/compiler/lib/src/js_backend/backend.dart
index 23fd25cbd900eefa2d649abe85b2a0e87676487c..529a254e929df6c7d258f664ad583a00dcb5a574 100644
--- a/pkg/compiler/lib/src/js_backend/backend.dart
+++ b/pkg/compiler/lib/src/js_backend/backend.dart
@@ -512,9 +512,6 @@ class JavaScriptBackend extends Backend {
   /// Holds the class for the [JsGetName] enum.
   EnumClassElement jsGetNameEnum;
 
-  /// Holds the class for the [JsBuiltins] enum.
-  EnumClassElement jsBuiltinEnum;
-
   /// True if a call to preserveMetadataMarker has been seen.  This means that
   /// metadata must be retained for dart:mirrors to work correctly.
   bool mustRetainMetadata = false;
@@ -2041,7 +2038,6 @@ class JavaScriptBackend extends Backend {
         preserveNamesMarker = find(library, 'preserveNames');
       } else if (uri == DART_EMBEDDED_NAMES) {
         jsGetNameEnum = find(library, 'JsGetName');
-        jsBuiltinEnum = find(library, 'JsBuiltin');
       } else if (uri == DART_HTML) {
         htmlLibraryIsLoaded = true;
       }