use symbol literals instead of const ctor in packages

pkg/mdv/test/node_bindings_test.dart

Index: pkg/mdv/test/node_bindings_test.dart
diff --git a/pkg/mdv/test/node_bindings_test.dart b/pkg/mdv/test/node_bindings_test.dart
index 2609d9ce066c21f4f766c3077e4ee1411dc00048..c13e5881409ee2aabe12e7d421213238461b4ffc 100644
--- a/pkg/mdv/test/node_bindings_test.dart
+++ b/pkg/mdv/test/node_bindings_test.dart
@@ -19,8 +19,6 @@ main() {
   group('Node Bindings', nodeBindingTests);
 }
 
-sym(x) => new Symbol(x);
-
 nodeBindingTests() {
   var testDiv;
 
@@ -39,12 +37,12 @@ nodeBindingTests() {
     text.bind('text', model, 'a');
     expect(text.text, '1');
 
-    model[sym('a')] = 2;
+    model[#a] = 2;
     performMicrotaskCheckpoint();
     expect(text.text, '2');
 
     text.unbind('text');
-    model[sym('a')] = 3;
+    model[#a] = 3;
     performMicrotaskCheckpoint();
     expect(text.text, '2');
 
@@ -61,17 +59,17 @@ nodeBindingTests() {
     expect(element.attributes['hidden'], '');
     expect(element.id, '2');
 
-    model[sym('a')] = null;
+    model[#a] = null;
     performMicrotaskCheckpoint();
     expect(element.attributes, isNot(contains('hidden')),
         reason: 'null is false-y');
 
-    model[sym('a')] = false;
+    model[#a] = false;
     performMicrotaskCheckpoint();
     expect(element.attributes, isNot(contains('hidden')));
 
-    model[sym('a')] = 'foo';
-    model[sym('b')] = 'x';
+    model[#a] = 'foo';
+    model[#b] = 'x';
     performMicrotaskCheckpoint();
     expect(element.attributes, contains('hidden'));
     expect(element.attributes['hidden'], '');
@@ -85,23 +83,23 @@ nodeBindingTests() {
     el.bind('value', model, 'x');
     expect(el.value, '42');
 
-    model[sym('x')] = 'Hi';
+    model[#x] = 'Hi';
     expect(el.value, '42', reason: 'changes delivered async');
     performMicrotaskCheckpoint();
     expect(el.value, 'Hi');
 
     el.value = 'changed';
     dispatchEvent('input', el);
-    expect(model[sym('x')], 'changed');
+    expect(model[#x], 'changed');
 
     el.unbind('value');
 
     el.value = 'changed again';
     dispatchEvent('input', el);
-    expect(model[sym('x')], 'changed');
+    expect(model[#x], 'changed');
 
     el.bind('value', model, 'x');
-    model[sym('x')] = null;
+    model[#x] = null;
     performMicrotaskCheckpoint();
     expect(el.value, '');
   }
@@ -116,20 +114,20 @@ nodeBindingTests() {
     input.bind('checked', model, 'x');
     expect(input.checked, true);
 
-    model[sym('x')] = false;
+    model[#x] = false;
     expect(input.checked, true);
     performMicrotaskCheckpoint();
     expect(input.checked, false,reason: 'model change should update checked');
 
     input.checked = true;
     dispatchEvent('change', input);
-    expect(model[sym('x')], true, reason: 'input.checked should set model');
+    expect(model[#x], true, reason: 'input.checked should set model');
 
     input.unbind('checked');
 
     input.checked = false;
     dispatchEvent('change', input);
-    expect(model[sym('x')], true,
+    expect(model[#x], true,
         reason: 'disconnected binding should not fire');
   });
 
@@ -141,16 +139,16 @@ nodeBindingTests() {
     input.bind('checked', model, 'x');
     expect(input.checked, true);
 
-    model[sym('x')] = false;
+    model[#x] = false;
     expect(input.checked, true, reason: 'changes delivered async');
     performMicrotaskCheckpoint();
     expect(input.checked, false);
 
     input.click();
-    expect(model[sym('x')], true);
+    expect(model[#x], true);
     performMicrotaskCheckpoint();
 
     input.click();
-    expect(model[sym('x')], false);
+    expect(model[#x], false);
   });
 }