Support lazy JS types.

pkg/dev_compiler/lib/js/es6/dart_sdk.js

Index: pkg/dev_compiler/lib/js/es6/dart_sdk.js
diff --git a/pkg/dev_compiler/lib/js/es6/dart_sdk.js b/pkg/dev_compiler/lib/js/es6/dart_sdk.js
index 17bea279fcdc1abc542e24720a6e5919274df243..754189cd3be0b018afd4eac498cbbcfd8a482bb8 100644
--- a/pkg/dev_compiler/lib/js/es6/dart_sdk.js
+++ b/pkg/dev_compiler/lib/js/es6/dart_sdk.js
@@ -1145,6 +1145,23 @@ dart.wrapType = function(type) {
   }
   return type[dart._typeObject] = new dart.WrappedType(type);
 };
+dart.lazyJSType = function(getJSTypeCallback, name) {
+  let key = getJSTypeCallback.toString();
+  if (dart._lazyJSTypes.has(key)) {
+    return dart._lazyJSTypes.get(key);
+  }
+  let ret = new dart.LazyJSType(getJSTypeCallback, name);
+  dart._lazyJSTypes.set(key, ret);
+  return ret;
+};
+dart.lazyAnonymousJSType = function(name) {
+  if (dart._lazyJSTypes.has(name)) {
+    return dart._lazyJSTypes.get(name);
+  }
+  let ret = new dart.LazyJSType(null, name);
+  dart._lazyJSTypes.set(name, ret);
+  return ret;
+};
 const _wrappedType = Symbol('_wrappedType');
 dart.unwrapType = function(obj) {
   return dart.dload(obj, _wrappedType);
@@ -1167,6 +1184,26 @@ dart.tagComputed = function(value, compute) {
 dart.tagLazy = function(value, compute) {
   dart.defineLazyProperty(value, dart._runtimeType, {get: compute});
 };
+const _jsTypeCallback = Symbol('_jsTypeCallback');
+const _rawJSType = Symbol('_rawJSType');
+dart._isInstanceOfLazyJSType = function(o, t) {
+  if (t[_jsTypeCallback] != null) {
+    return dart.is(o, t[_rawJSType]);
+  }
+  if (o == null) return false;
+  return dart._isJSObject(o);
+};
+dart._asInstanceOfLazyJSType = function(o, t) {
+  if (t[_jsTypeCallback] != null) {
+    return dart.as(o, t[_rawJSType]);
+  }
+  if (o == null) return null;
+  if (!dart.test(dart._isJSObject(o))) dart._throwCastError(o, t, true);
+  return o;
+};
+dart._isJSObject = function(o) {
+  return !dart.getReifiedType(o)[dart._runtimeType];
+};
 dart._initialize2 = function() {
   dart.TypeRep.prototype.is = function is_T(object) {
     return dart.is(object, this);
@@ -1186,6 +1223,12 @@ dart._initialize2 = function() {
   dart.Dynamic.prototype._check = function check_Dynamic(object) {
     return object;
   };
+  dart.LazyJSType.prototype.is = function is_T(object) {
+    return dart._isInstanceOfLazyJSType(object, this);
+  };
+  dart.LazyJSType.prototype.as = function as_T(object) {
+    return dart._asInstanceOfLazyJSType(object, this);
+  };
 };
 dart._functionType = function(definite, returnType, args, extra) {
   if (args === void 0 && extra === void 0) {
@@ -1248,6 +1291,11 @@ dart.getImplicitFunctionType = function(type) {
 dart.isFunctionType = function(type) {
   return type instanceof dart.AbstractFunctionType || type === core.Function;
 };
+dart.isLazyJSSubtype = function(t1, t2, covariant) {
+  if (dart.equals(t1, t2)) return true;
+  if (t1[_jsTypeCallback] == null || t2[_jsTypeCallback] == null) return true;
+  return dart.isClassSubType(t1[_rawJSType], t2[_rawJSType], covariant);
+};
 dart.isFunctionSubtype = function(ft1, ft2, covariant) {
   if (ft2 === core.Function) {
     return true;
@@ -1343,6 +1391,9 @@ dart._isSubtype = function(t1, t2, covariant) {
   if (dart.isFunctionType(t1) && dart.isFunctionType(t2)) {
     return dart.isFunctionSubtype(t1, t2, covariant);
   }
+  if (t1 instanceof dart.LazyJSType && t2 instanceof dart.LazyJSType) {
+    return dart.isLazyJSSubtype(t1, t2, covariant);
+  }
   return false;
 };
 dart.isClassSubType = function(t1, t2, covariant) {
@@ -2064,6 +2115,12 @@ dart._extensionType = Symbol("extensionType");
 dart.dartx = dartx;
 dart._runtimeType = Symbol("_runtimeType");
 dart.isNamedConstructor = Symbol("isNamedConstructor");
+dart.defineLazy(dart, {
+  get _lazyJSTypes() {
+    return new Map();
+  },
+  set _lazyJSTypes(_) {}
+});
 dart.metadata = Symbol("metadata");
 dart._typeObject = Symbol("typeObject");
 core.Object = class Object {
@@ -2134,6 +2191,28 @@ dart.Dynamic = class Dynamic extends dart.TypeRep {
     return 'dynamic';
   }
 };
+const _dartName = Symbol('_dartName');
+dart.LazyJSType = class LazyJSType extends core.Object {
+  new(jsTypeCallback, dartName) {
+    this[_jsTypeCallback] = jsTypeCallback;
+    this[_dartName] = dartName;
+  }
+  get [_rawJSType]() {
+    return this[_jsTypeCallback]();
+  }
+  toString() {
+    return core.String._check(this[_jsTypeCallback] != null ? dart.typeName(this[_rawJSType]) : this[_dartName]);
+  }
+};
+dart.LazyJSType[dart.implements] = () => [core.Type];
+dart.setSignature(dart.LazyJSType, {
+  constructors: () => ({new: dart.definiteFunctionType(dart.LazyJSType, [dart.dynamic, dart.dynamic])}),
+  fields: () => ({
+    [_jsTypeCallback]: dart.dynamic,
+    [_dartName]: dart.dynamic
+  }),
+  getters: () => ({[_rawJSType]: dart.definiteFunctionType(dart.dynamic, [])})
+});
 dart.dynamic = new dart.Dynamic();
 dart._initialize = dart._initialize2();
 dart.Void = class Void extends dart.TypeRep {