Do not allow platform prefices to conflict with fixed members.

lib/compiler/implementation/dart_backend/renamer.dart

 // Copyright (c) 2012, 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.
 
 Function get _compareNodes =>
     compareBy((n) => n.getBeginToken().charOffset);
 
 typedef String _Renamer(Renamable renamable);
 abstract class Renamable {
   const int RENAMABLE_TYPE_ELEMENT = 1;
@@ skipping 95 matching lines @@
   // Renamer function that takes library and original name and returns a new
   // name for given identifier.
   Function rename;
   // A function that takes original identifier name and generates a new unique
   // identifier.
   Function generateUniqueName;
   if (compiler.enableMinification) {
     MinifyingGenerator generator = new MinifyingGenerator();
     Set<String> forbiddenIdentifiers = new Set<String>.from(['main']);
     forbiddenIdentifiers.addAll(Keyword.keywords.getKeys());
+    forbiddenIdentifiers.addAll(fixedMemberNames);
     generateUniqueName = (_) =>
         generator.generate(forbiddenIdentifiers.contains);
     rename = makeRenamer(generateUniqueName);
     Function renameElement = makeElementRenamer(rename, generateUniqueName);
 
     Set<String> allParameterIdentifiers = new Set<String>();
     for (var functionScope in placeholderCollector.functionScopes.getValues()) {
       allParameterIdentifiers.addAll(functionScope.parameterIdentifiers);
     }
     // Build a sorted (by usage) list of local nodes that will be renamed to
@@ skipping 16 matching lines @@
         allSortedLocals[i].addAll(currentSortedNodes[i]);
       }
     }
 
     // Rename elements, members and locals together based on their usage count,
     // otherwise when we rename elements first there will be no good identifiers
     // left for members even if they are used often.
     String elementRenamer(ElementRenamable elementRenamable) =>
         renameElement(elementRenamable.element);
     String memberRenamer(MemberRenamable memberRenamable) =>
-        generator.generate((name) =>
-            forbiddenIdentifiers.contains(name)
-            || fixedMemberNames.contains(name));
+        generator.generate(forbiddenIdentifiers.contains);
     String localRenamer(LocalRenamable localRenamable) =>
         generator.generate((name) =>
             allParameterIdentifiers.contains(name)
-            || forbiddenIdentifiers.contains(name)
-            || fixedMemberNames.contains(name));
+            || forbiddenIdentifiers.contains(name));
     List<Renamable> renamables = [];
     placeholderCollector.elementNodes.forEach(
         (Element element, Set<Node> nodes) {
       renamables.add(new ElementRenamable(element, nodes, elementRenamer));
     });
     placeholderCollector.memberPlaceholders.forEach(
         (String memberName, Set<Identifier> identifiers) {
       renamables.add(
           new MemberRenamable(memberName, identifiers, memberRenamer));
     });
@@ skipping 118 matching lines @@
     index ~/= firstCharAlphabet.length;
     int length = otherCharsAlphabet.length;
     while (index >= length) {
       resultBuilder.add(otherCharsAlphabet[index % length]);
       index ~/= length;
     }
     resultBuilder.add(otherCharsAlphabet[index]);
     return resultBuilder.toString();
   }
 }