1. Dynamic compute the main closure that needs to be run by the main isolate

runtime/vm/dart_api_impl.cc

 // Copyright (c) 2013, 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.
 
 #include "include/dart_api.h"
 #include "include/dart_mirrors_api.h"
 #include "include/dart_native_api.h"
 
 #include "lib/stacktrace.h"
 #include "platform/assert.h"
@@ skipping 2325 matching lines @@
   DARTSCOPE(Thread::Current());
   const Double& obj = Api::UnwrapDoubleHandle(Z, double_obj);
   if (obj.IsNull()) {
     RETURN_TYPE_ERROR(Z, double_obj, Double);
   }
   *value = obj.value();
   return Api::Success();
 }
 
 
+DART_EXPORT Dart_Handle Dart_GetClosure(Dart_Handle library,
+                                        Dart_Handle function_name) {
+  DARTSCOPE(Thread::Current());
+  const Library& lib = Api::UnwrapLibraryHandle(Z, library);
+  if (lib.IsNull()) {
+    RETURN_TYPE_ERROR(Z, library, Library);
+  }
+  const String& name = Api::UnwrapStringHandle(Z, function_name);
+  if (name.IsNull()) {
+    RETURN_TYPE_ERROR(Z, function_name, String);
+  }
+  return Api::NewHandle(T, lib.GetFunctionClosure(name));
+}
+
+
 // --- Booleans ----
 
 DART_EXPORT Dart_Handle Dart_True() {
   ASSERT(Isolate::Current() != NULL);
   return Api::True();
 }
 
 
 DART_EXPORT Dart_Handle Dart_False() {
   ASSERT(Isolate::Current() != NULL);
@@ skipping 3059 matching lines @@
 
   // NOTE: Now the VM owns the [kernel_program] memory!  Currently we do not
   // free it because (similar to the token stream) it will be used to repeatedly
   // run the `kernel::FlowGraphBuilder()`.
   kernel::KernelReader reader(
       reinterpret_cast<kernel::Program*>(kernel_program));
   const Object& tmp = reader.ReadProgram();
   if (tmp.IsError()) {
     return Api::NewHandle(T, tmp.raw());
   }
+  // TODO(kernel): Setting root library based on whether it has 'main' or not
+  // is not correct because main can be in the exported namespace of a library
+  // or it could be a getter.
   if (tmp.IsNull()) {
     return Api::NewError("%s: The binary program does not contain 'main'.",
                          CURRENT_FUNC);
   }
   library ^= tmp.raw();
   I->object_store()->set_root_library(library);
   return Api::NewHandle(T, library.raw());
 #endif
 }
 
@@ skipping 1513 matching lines @@
 }
 
 
 DART_EXPORT void Dart_DumpNativeStackTrace(void* context) {
 #ifndef PRODUCT
   Profiler::DumpStackTrace(context);
 #endif
 }
 
 }  // namespace dart