dart2js: Reuse names for constructor bodes.

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

 // Copyright (c) 2011, 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.
 
 part of js_backend;
 
 /**
  * Assigns JavaScript identifiers to Dart variables, class-names and members.
  *
  * Names are generated through three stages:
@@ skipping 567 matching lines @@
 
   String _proposeNameForConstructorBody(ConstructorBodyElement method) {
     String name = Elements.reconstructConstructorNameSourceString(method);
     // We include the method suffix on constructor bodies. It has no purpose,
     // but this way it produces the same names as previous versions of the
     // Namer class did.
     List<String> suffix = callSuffixForSignature(method.functionSignature);
     return '$name\$${suffix.join(r'$')}';
   }
 
+  /// Name for a constructor body.
+  jsAst.Name constructorBodyName(FunctionElement ctor) {
+    return _disambiguateInternalMember(ctor,
+        () => _proposeNameForConstructorBody(ctor));
+  }
+
   /// Annotated name for [method] encoding arity and named parameters.
   jsAst.Name instanceMethodName(FunctionElement method) {
     if (method.isGenerativeConstructorBody) {
-      return _disambiguateInternalMember(method,
-          () => _proposeNameForConstructorBody(method));
+      return constructorBodyName(method);
     }
     return invocationName(new Selector.fromElement(method));
   }
 
   /// Annotated name for a public method with the given [originalName]
   /// and [arity] and no named parameters.
   jsAst.Name publicInstanceMethodNameByArity(String originalName,
                                              int arity) {
     return invocationName(new Selector.call(originalName, null, arity));
   }
@@ skipping 307 matching lines @@
         proposedName += r'$' + suffixes.join(r'$');
       }
       newName = getFreshName(proposedName,
                              usedInstanceNames, suggestedInstanceNames,
                              sanitizeForAnnotations: true);
       userInstanceMembers[key] = newName;
     }
     return newName;
   }
 
+  /// Returns the disambiguated name for the instance member identified by
+  /// [key].
+  ///
+  /// When a name for an element is requested by key, it may not be requested
+  /// by element at the same time, as two different names would be returned.
+  ///
+  /// If key has not yet been registered, [proposeName] is used to generate
+  /// a name proposal for the given key.
+  ///
+  /// [key] must not clash with valid instance names. This is typically
+  /// achieved by using at least one character in [key] that is not valid in
+  /// identifiers, for example the @ symbol.
+  jsAst.Name _disambiguateMemberByKey(String key, String proposeName()) {
+    jsAst.Name newName = userInstanceMembers[key];
+    if (newName == null) {
+      String name = proposeName();
+      newName = getFreshName(name,
+                             usedInstanceNames, suggestedInstanceNames,
+                             sanitizeForAnnotations: true);
+      userInstanceMembers[key] = newName;
+    }
+    return newName;
+  }
+
   /// Forces the public instance member with [originalName] to have the given
   /// [disambiguatedName].
   ///
   /// The [originalName] must not have been disambiguated before, and the
   /// [disambiguatedName] must not have been used.
   ///
   /// Using [_disambiguateMember] with the given [originalName] and no suffixes
   /// will subsequently return [disambiguatedName].
   void reservePublicMemberName(String originalName,
                                String disambiguatedName) {
@@ skipping 1107 matching lines @@
         if (!first) {
           sb.write('_');
         }
         sb.write('_');
         visit(parameter);
         first = true;
       }
     }
   }
 }