support the JS builtin

test/codegen/expect/_js_names/_js_names.js

 var _js_names;
 (function(_js_names) {
   'use strict';
   // Function preserveNames: () → dynamic
   function preserveNames() {
   }
   dart.defineLazyProperties(_js_names, {
     get mangledNames() {
       return computeMangledNames(_foreign_helper.JS_EMBEDDED_GLOBAL('=Object', dart.as(_js_embedded_names.MANGLED_NAMES, core.String)), false);
     },
     get reflectiveNames() {
       return computeReflectiveNames(_js_names.mangledNames);
     },
     get mangledGlobalNames() {
       return computeMangledNames(_foreign_helper.JS_EMBEDDED_GLOBAL('=Object', dart.as(_js_embedded_names.MANGLED_GLOBAL_NAMES, core.String)), true);
     },
     get reflectiveGlobalNames() {
       return computeReflectiveNames(_js_names.mangledGlobalNames);
     }
   });
   // Function computeMangledNames: (dynamic, bool) → Map<String, String>
   function computeMangledNames(jsMangledNames, isGlobal) {
     preserveNames();
     let keys = extractKeys(jsMangledNames);
     let result = dart.map();
     let getterPrefix = _foreign_helper.JS_GET_NAME('GETTER_PREFIX');
     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)) {
           result.set(`${setterPrefix}${key.substring(getterPrefixLength)}`, `${value}=`);
         }
       }
     }
     return result;
   }
   // Function computeReflectiveNames: (Map<String, String>) → Map
   function computeReflectiveNames(map) {
     preserveNames();
     let result = dart.map();
     map.forEach((mangledName, reflectiveName) => {
       result.set(reflectiveName, mangledName);
     });
     return result;
   }
   // 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
   function unmangleGlobalNameIfPreservedAnyways(name) {
     let names = _foreign_helper.JS_EMBEDDED_GLOBAL('=Object', dart.as(_js_embedded_names.MANGLED_GLOBAL_NAMES, core.String));
     return dart.as(_js_helper.JsCache.fetch(names, name), core.String);
   }
   // 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;
   _js_names.computeMangledNames = computeMangledNames;
   _js_names.computeReflectiveNames = computeReflectiveNames;
   _js_names.extractKeys = extractKeys;
   _js_names.unmangleGlobalNameIfPreservedAnyways = unmangleGlobalNameIfPreservedAnyways;
   _js_names.unmangleAllIdentifiersIfPreservedAnyways = unmangleAllIdentifiersIfPreservedAnyways;
 })(_js_names || (_js_names = {}));