pkg/compiler: fix imports

pkg/compiler/lib/src/cps_ir/update_refinements.dart

 library dart2js.cps_ir.update_refinements;
 
+import '../world.dart';
 import 'cps_ir_nodes.dart';
 import 'optimizers.dart' show Pass;
 import 'type_mask_system.dart';
-import '../world.dart';
 
 /// Updates all references to use the most refined version in scope.
 ///
 /// [GVN] and [RedundantJoinElimination], and possibly other passes, can create
 /// references that don't use the best refinement in scope. This pass improves
 /// the refinement information.
 ///
 //
 // TODO(asgerf): Could be done during GVN for another adjacent pass.
 //   It is easier to measure performance and rearrange passes when it has its
@@ skipping 74 matching lines @@
     if (def is Primitive) {
       Primitive refinement = refinementFor[def.effectiveDefinition];
       if (refinement != null && refinement != ref.definition) {
         ref.changeTo(refinement);
         return true;
       }
     }
     return false;
   }
 }