Flesh out dynamic invocation code

test/codegen/expect/dart/_js_helper.js

 var _js_helper;
 (function(exports) {
   'use strict';
   class _Patch extends dart.Object {
     _Patch() {
     }
   }
   let patch = new _Patch();
   class InternalMap extends dart.Object {
   }
@@ skipping 3687 matching lines @@
   // Function isJsArray: (dynamic) → bool
   function isJsArray(value) {
     return dart.is(value, _interceptors.JSArray);
   }
   // Function hasField: (dynamic, dynamic) → dynamic
   function hasField(object, name) {
     return name in object;
   }
   // Function hasNoField: (dynamic, dynamic) → dynamic
   function hasNoField(object, name) {
-    return dart.throw_("Unimplemented PrefixExpression: !hasField(object, name)");
+    return dart.dunary('!', hasField(object, name));
   }
   // Function isJsFunction: (dynamic) → bool
   function isJsFunction(o) {
     return typeof o == "function";
   }
   // Function isJsObject: (dynamic) → bool
   function isJsObject(o) {
     return typeof o == 'object';
   }
   // Function isIdentical: (dynamic, dynamic) → bool
@@ skipping 229 matching lines @@
   exports.getIndex = getIndex;
   exports.getLength = getLength;
   exports.isJsArray = isJsArray;
   exports.hasField = hasField;
   exports.hasNoField = hasNoField;
   exports.isJsFunction = isJsFunction;
   exports.isJsObject = isJsObject;
   exports.isIdentical = isIdentical;
   exports.isNotIdentical = isNotIdentical;
 })(_js_helper || (_js_helper = {}));