pkg/compiler: fix imports

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

 library dart2js.cps_ir_integrity;
 
+import '../tracer.dart' as tracer;
 import 'cps_ir_nodes.dart';
 import 'cps_ir_nodes_sexpr.dart';
-import '../tracer.dart' as tracer;
 
 /// Dump S-expressions on error if the tracer is enabled.
 ///
 /// Technically this has nothing to do with the tracer, but if you want one
 /// enabled, you typically want the other as well, so we use the same flag.
 const bool ENABLE_DUMP = tracer.TRACE_FILTER_PATTERN != null;
 
 enum ScopeType { InScope, InDefinition, NotInScope }
 
 /// Performs integrity checks on the CPS IR.
@@ skipping 251 matching lines @@
   }
 
   @override
   processReference(Reference node) {
     if (node.parent != _parent) {
       error('Parent pointer on $node is ${node.parent} but should be $_parent',
           node);
     }
   }
 }