Avoid known native field names when minifying method names.

sdk/lib/_internal/compiler/implementation/js_backend/minify_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.
  */
 class MinifyNamer extends Namer {
-  MinifyNamer(Compiler compiler) : super(compiler);
+  MinifyNamer(Compiler compiler) : super(compiler) {
+    reserveBackendNames();
+  }
 
   String get isolateName => 'I';
   String get isolatePropertiesName => 'p';
   bool get shouldMinify => true;
 
   const ALPHABET_CHARACTERS = 52;  // a-zA-Z.
   const ALPHANUMERIC_CHARACTERS = 62;  // a-zA-Z0-9.
 
   // You can pass an invalid identifier to this and unlike its non-minifying
   // counterpart it will never return the proposedName as the new fresh name.
   String getFreshName(String proposedName, Set<String> usedNames) {
     var freshName = _getUnusedName(proposedName, usedNames);
     usedNames.add(freshName);
     return freshName;
   }
 
   SourceString getClosureVariableName(SourceString name, int id) {
     if (id < ALPHABET_CHARACTERS) {
       return new SourceString(new String.fromCharCodes([_letterNumber(id)]));
     }
     return new SourceString("${getMappedInstanceName('closure')}_$id");
   }
 
+  void reserveBackendNames() {
+    for (var name in JsNames.reservedNativeProperties) {
+      if (name.length < 3) {

[ngeoffray, 2012/12/18 12:34:03]

What does this mean? Why 3?

+        instanceNameMap[name] = name;
+      }
+      usedInstanceNames.add(name);
+    }
+  }
+
   // This gets a minified name based on a hash of the proposed name.  This
   // is slightly less efficient than just getting the next name in a series,
   // but it means that small changes in the input program will give smallish
   // changes in the output, which can be useful for diffing etc.
   String _getUnusedName(String proposedName, Set<String> usedNames) {
     // Try single-character names with characters that occur in the
     // input.
     for (int i = 0; i < proposedName.length; i++) {
       String candidate = proposedName[i];
       int code = candidate.charCodeAt(0);
@@ skipping 61 matching lines @@
   }
 
   int _alphaNumericNumber(int x) {
     if (x >= ALPHANUMERIC_CHARACTERS) x %= ALPHANUMERIC_CHARACTERS;
     if (x < 26) return $a + x;
     if (x < 52) return $A + x - 26;
     return $0 + x - 52;
   }
 
 }