support the JS builtin

test/codegen/expect/_js_names/_js_names.js

Index: test/codegen/expect/_js_names/_js_names.js
diff --git a/test/codegen/expect/_js_names/_js_names.js b/test/codegen/expect/_js_names/_js_names.js
index c7410d41ad27e017ec2a3d17dea54b9be66e8152..804cdd9630cc9fddf93c641b73892c9d57aadff7 100644
--- a/test/codegen/expect/_js_names/_js_names.js
+++ b/test/codegen/expect/_js_names/_js_names.js
@@ -27,7 +27,7 @@ var _js_names;
     let getterPrefixLength = getterPrefix.length;
     let setterPrefix = _foreign_helper.JS_GET_NAME('SETTER_PREFIX');
     for (let key of keys) {
-      let value = dart.as(_foreign_helper.JS('String', '#[#]', jsMangledNames, key), core.String);
+      let value = jsMangledNames[key];
       result.set(key, value);
       if (!dart.notNull(isGlobal)) {
         if (key.startsWith(getterPrefix)) {
@@ -48,7 +48,14 @@ var _js_names;
   }
   // Function extractKeys: (dynamic) → List<dynamic>
   function extractKeys(victim) {
-    let result = _foreign_helper.JS('', '\n(function(victim, hasOwnProperty) {\n  var result = [];\n  for (var key in victim) {\n    if (hasOwnProperty.call(victim, key)) result.push(key);\n  }\n  return result;\n})(#, Object.prototype.hasOwnProperty)', victim);
+    let result = function(victim, hasOwnProperty) {
+      var result = [];
+      for (var key in victim) {
+        if (hasOwnProperty.call(victim, key))
+          result.push(key);
+      }
+      return result;
+    }(victim, Object.prototype.hasOwnProperty);
     return new _interceptors.JSArray.markFixed(result);
   }
   // Function unmangleGlobalNameIfPreservedAnyways: (String) → String
@@ -58,7 +65,9 @@ var _js_names;
   }
   // Function unmangleAllIdentifiersIfPreservedAnyways: (String) → String
   function unmangleAllIdentifiersIfPreservedAnyways(str) {
-    return dart.as(_foreign_helper.JS("String", "(#).replace(/[^<,> ]+/g," + "function(m) { return #[m] || m; })", str, _foreign_helper.JS_EMBEDDED_GLOBAL('', dart.as(_js_embedded_names.MANGLED_GLOBAL_NAMES, core.String))), core.String);
+    return str.replace(/[^<,> ]+/g, function(m) {
+      return _foreign_helper.JS_EMBEDDED_GLOBAL('', dart.as(_js_embedded_names.MANGLED_GLOBAL_NAMES, core.String))[m] || m;
+    });
   }
   // Exports:
   _js_names.preserveNames = preserveNames;