Move remaining helpers to BackendHelpers

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 '../common.dart';
 import '../common/registry.dart' show Registry;
 import '../compiler.dart' show Compiler;
@@ skipping 50 matching lines @@
 ///
 ///   * Include all generic-type arguments, if the program uses type
 ///   variables in expressions such as `class A<T> { Type get extract => T }`.
 ///
 // TODO(sigmund): add support for const expressions, currently this
 // implementation only supports Type literals. To support const expressions we
 // need to change some of the invariants below (e.g. we can no longer use the
 // ClassElement of a type to refer to keys we need to discover).
 // TODO(sigmund): detect uses of mirrors
 class LookupMapAnalysis {
+  static final Uri PACKAGE_LOOKUP_MAP =
+      new Uri(scheme: 'package', path: 'lookup_map/lookup_map.dart');
+
   /// Reference to [JavaScriptBackend] to be able to enqueue work when we
   /// discover that a key in a map is potentially used.
   final JavaScriptBackend backend;
 
   /// Reference the diagnostic reporting system for logging and reporting issues
   /// to the end-user.
   final DiagnosticReporter reporter;
 
   /// The resolved [VariableElement] associated with the top-level `_version`.
   VariableElement lookupMapVersionVariable;
@@ skipping 351 matching lines @@
       }
     } else {
       original.fields[analysis.entriesField] =
           new ListConstantValue(listType, keyValuePairs);
     }
   }
 }
 
 final _validLookupMapVersionConstraint =
     new VersionConstraint.parse('^0.0.1');