Rework standalone to use a synchronous loader that does not invoke Dart code

runtime/bin/isolate_data.h

 // Copyright (c) 2012, 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.
 
 #ifndef BIN_ISOLATE_DATA_H_
 #define BIN_ISOLATE_DATA_H_
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "platform/globals.h"
 
 namespace dart {
 namespace bin {
 
 // Forward declaration.
 class EventHandler;
+class Loader;
 
 // Data associated with every isolate in the standalone VM
 // embedding. This is used to free external resources for each isolate
 // when the isolate shuts down.
 class IsolateData {
  public:
   IsolateData(const char* url,
               const char* package_root,
               const char* packages_file)
       : script_url((url != NULL) ? strdup(url) : NULL),
         package_root(NULL),
         packages_file(NULL),
         udp_receive_buffer(NULL),
-        builtin_lib_(NULL) {
+        builtin_lib_(NULL),
+        loader_(NULL) {
     if (package_root != NULL) {
       ASSERT(packages_file == NULL);
       this->package_root = strdup(package_root);
     } else if (packages_file != NULL) {
       this->packages_file = strdup(packages_file);
     }
   }
 
   ~IsolateData() {
     free(script_url);
@@ skipping 19 matching lines @@
     ASSERT(lib != NULL);
     ASSERT(!Dart_IsError(lib));
     builtin_lib_ = Dart_NewPersistentHandle(lib);
   }
 
   char* script_url;
   char* package_root;
   char* packages_file;
   uint8_t* udp_receive_buffer;
 
+  // While loading a loader is associated with the isolate.
+  bool HasLoader() const { return loader_ != NULL; }
+  Loader* loader() const {
+    ASSERT(loader_ != NULL);
+    return loader_;
+  }
+  void set_loader(Loader* loader) {
+    ASSERT((loader_ == NULL) || (loader == NULL));
+    loader_ = loader;
+  }
+
  private:
   Dart_Handle builtin_lib_;
+  Loader* loader_;
 
   DISALLOW_COPY_AND_ASSIGN(IsolateData);
 };
 
 }  // namespace bin
 }  // namespace dart
 
 #endif  // BIN_ISOLATE_DATA_H_