Collect getters in a FunctionSet while resolving.

tests/compiler/dart2js/gvn_dynamic_field_get_test.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.
+// Test that dart2js gvns dynamic getters that don't have side
+// effects.
+
+#import('compiler_helper.dart');
+#import('parser_helper.dart');
+#import('dart:uri');
+
+const String TEST = @"""
+class A {
+  var foo;
+  bar(a) {
+    return a.foo + a.foo;
+  }
+}
+
+main() {
+  new A().bar(new Object());
+}
+""";
+
+main() {
+  Uri uri = new Uri.fromComponents(scheme: 'source');
+  var compiler = compilerFor(TEST, uri);
+  compiler.runCompiler(uri);
+  String generated = compiler.assembledCode;
+  RegExp regexp = const RegExp(@"get\$foo");
+  Iterator matches = regexp.allMatches(generated).iterator();
+  checkNumberOfMatches(matches, 1);
+  var cls = findElement(compiler, 'A');
+  Expect.isNotNull(cls);
+  var element = cls.lookupLocalMember(buildSourceString('foo'));
+  Expect.isNotNull(element);
+  Expect.isFalse(compiler.world.userDefinedGetters.contains(element));
+}