Add toStructuredText to ConstantExpression and align method names with ConstantValue

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

 // Copyright (c) 2015, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// Analysis to determine how to generate code for `LookupMap`s.
 library compiler.src.js_backend.lookup_map_analysis;
 
 import 'package:pub_semver/pub_semver.dart';
 
 import '../common.dart';
@@ skipping 290 matching lines @@
 
     // When --verbose is passed, we show the total number and set of keys that
     // were tree-shaken from lookup maps.
     Compiler compiler = backend.compiler;
     if (compiler.options.verbose) {
       var sb = new StringBuffer();
       int count = 0;
       for (var info in _lookupMaps.values) {
         for (var key in info.unusedEntries.keys) {
           if (count != 0) sb.write(',');
-          sb.write(key.unparse());
+          sb.write(key.toDartText());
           count++;
         }
       }
       reporter.log(count == 0
           ? 'lookup-map: nothing was tree-shaken'
           : 'lookup-map: found $count unused keys ($sb)');
     }
 
     // Release resources.
     _lookupMaps.clear();
@@ skipping 107 matching lines @@
         original.fields[analysis.valueField] = keyValuePairs[1];
       }
     } else {
       original.fields[analysis.entriesField] =
           new ListConstantValue(listType, keyValuePairs);
     }
   }
 }
 
 final _validLookupMapVersionConstraint = new VersionConstraint.parse('^0.0.1');