Revert "Parts must start with 'part of'" and "Attempt to fix VM build"

dart/samples/tests/samples/lib/layout/css.dart

-part of layout_tests;
-
 // File generated by Dart CSS from source file layout.scss
 // Do not edit.
 
 class AdaptiveLayout {
   // selector, properties<propertyName, value>
   static const selectors = const {
     '#grid' : const {
       'display' : '-dart-grid',
       'grid-columns' : 'auto minmax(min-content, 1fr)',
       'grid-rows' : 'auto minmax(min-content, 1fr) auto',
@@ skipping 328 matching lines @@
       'grid-layer' : '5',
       'grid-column-align' : 'center',
       'grid-row-align' : 'center',
     },
   };
 }
 
 class CSS {
   // CSS class selectors:
 }