Avoid known native field names when minifying method names.

sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart

Index: sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart
diff --git a/sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart b/sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart
index 5d176c1530b5a60ed06675f8fbcf9d57c45e400a..9a512d8adb7026f26cf1568dad12d547203d92ca 100644
--- a/sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart
+++ b/sdk/lib/_internal/compiler/implementation/js_backend/minify_namer.dart
@@ -8,7 +8,9 @@ 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';
@@ -32,6 +34,15 @@ class MinifyNamer extends Namer {
     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