Make json-maps implement Map<String, dynamic>.

tests/corelib/map_test.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.
 
 library map_test;
 
 import "package:expect/expect.dart";
 import 'dart:collection';
 import 'dart:convert' show JSON;
 
 Map newJsonMap() => JSON.decode('{}');
 Map newJsonMapCustomReviver() =>
     JSON.decode('{}', reviver: (key, value) => value);
 
 void main() {
   test(new HashMap());
   test(new LinkedHashMap());
   test(new SplayTreeMap());
   test(new SplayTreeMap(Comparable.compare));
   test(new MapView(new HashMap()));
   test(new MapView(new SplayTreeMap()));
   test(new MapBaseMap());
   test(new MapMixinMap());
-  test(newJsonMap());
-  test(newJsonMapCustomReviver());
   testLinkedHashMap();
   testMapLiteral();
   testNullValue();
   testTypes();
 
   testWeirdStringKeys(new Map());
   testWeirdStringKeys(new Map<String, String>());
   testWeirdStringKeys(new HashMap());
   testWeirdStringKeys(new HashMap<String, String>());
   testWeirdStringKeys(new LinkedHashMap());
@@ skipping 10 matching lines @@
   testNumericKeys(new HashMap());
   testNumericKeys(new HashMap<num, String>());
   testNumericKeys(new HashMap.identity());
   testNumericKeys(new HashMap<num, String>.identity());
   testNumericKeys(new LinkedHashMap());
   testNumericKeys(new LinkedHashMap<num, String>());
   testNumericKeys(new LinkedHashMap.identity());
   testNumericKeys(new LinkedHashMap<num, String>.identity());
   testNumericKeys(new MapBaseMap<num, String>());
   testNumericKeys(new MapMixinMap<num, String>());
-  testNumericKeys(newJsonMap());
-  testNumericKeys(newJsonMapCustomReviver());
 
   testNaNKeys(new Map());
   testNaNKeys(new Map<num, String>());
   testNaNKeys(new HashMap());
   testNaNKeys(new HashMap<num, String>());
   testNaNKeys(new LinkedHashMap());
   testNaNKeys(new LinkedHashMap<num, String>());
   testNaNKeys(new MapBaseMap<num, String>());
   testNaNKeys(new MapMixinMap<num, String>());
-  testNaNKeys(newJsonMap());
-  testNaNKeys(newJsonMapCustomReviver());
   // Identity maps fail the NaN-keys tests because the test assumes that
   // NaN is not equal to NaN.
 
   testIdentityMap(new Map.identity());
   testIdentityMap(new HashMap.identity());
   testIdentityMap(new LinkedHashMap.identity());
   testIdentityMap(new HashMap(equals: identical, hashCode: identityHashCode));
   testIdentityMap(
       new LinkedHashMap(equals: identical, hashCode: identityHashCode));
   testIdentityMap(new HashMap(
@@ skipping 10 matching lines @@
       hashCode: myHashCode,
       isValidKey: (v) => v is Customer));
   testCustomMap(
       new HashMap<Customer, dynamic>(equals: myEquals, hashCode: myHashCode));
 
   testCustomMap(new LinkedHashMap<Customer, dynamic>(
       equals: myEquals, hashCode: myHashCode));
 
   testIterationOrder(new LinkedHashMap());
   testIterationOrder(new LinkedHashMap.identity());
-  testIterationOrder(newJsonMap());
-  testIterationOrder(newJsonMapCustomReviver());
 
   testOtherKeys(new SplayTreeMap<int, int>());
   testOtherKeys(
       new SplayTreeMap<int, int>((int a, int b) => a - b, (v) => v is int));
   testOtherKeys(new SplayTreeMap((int a, int b) => a - b, (v) => v is int));
   testOtherKeys(new HashMap<int, int>());
   testOtherKeys(new HashMap<int, int>.identity());
   testOtherKeys(new HashMap<int, int>(
       hashCode: (v) => v.hashCode, isValidKey: (v) => v is int));
   testOtherKeys(new HashMap(
       equals: (int x, int y) => x == y,
       hashCode: (int v) => v.hashCode,
       isValidKey: (v) => v is int));
   testOtherKeys(new LinkedHashMap<int, int>());
   testOtherKeys(new LinkedHashMap<int, int>.identity());
   testOtherKeys(new LinkedHashMap<int, int>(
       hashCode: (v) => v.hashCode, isValidKey: (v) => v is int));
   testOtherKeys(new LinkedHashMap(
       equals: (int x, int y) => x == y,
       hashCode: (int v) => v.hashCode,
       isValidKey: (v) => v is int));
   testOtherKeys(new MapBaseMap<int, int>());
   testOtherKeys(new MapMixinMap<int, int>());
-  testOtherKeys(newJsonMap());
-  testOtherKeys(newJsonMapCustomReviver());
 
   testUnmodifiableMap(const {1: 37});
   testUnmodifiableMap(new UnmodifiableMapView({1: 37}));
   testUnmodifiableMap(new UnmodifiableMapBaseMap([1, 37]));
 
   testFrom();
 }
 
 void test(Map map) {
   testDeletedElement(map);
@@ skipping 839 matching lines @@
   Map<Interface, Interface> interfaceMap = <Interface, Interface>{sub: sub};
   expectMap(superMap, new Map<Super, Super>.from(interfaceMap));
   expectMap(superMap, new Map<Interface, Interface>.from(superMap));
   expectMap(superMap, new HashMap<Super, Super>.from(interfaceMap));
   expectMap(superMap, new HashMap<Interface, Interface>.from(superMap));
   expectMap(superMap, new LinkedHashMap<Super, Super>.from(interfaceMap));
   expectMap(superMap, new LinkedHashMap<Interface, Interface>.from(superMap));
   expectMap(superMap, new SplayTreeMap<Super, Super>.from(interfaceMap));
   expectMap(superMap, new SplayTreeMap<Interface, Interface>.from(superMap));
 }