Fix the front end compiler tests.

runtime/vm/kernel_reader.cc

 // Copyright (c) 2016, 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 "vm/kernel_reader.h"
 
 #include <string.h>
 
 #include "vm/dart_api_impl.h"
 #include "vm/longjump.h"
@@ skipping 138 matching lines @@
       ReadLibrary(kernel_library);
     }
 
     for (intptr_t i = 0; i < length; i++) {
       dart::Library& library =
           LookupLibrary(program_->libraries()[i]->canonical_name());
       if (!library.Loaded()) library.SetLoaded();
     }
 
     if (ClassFinalizer::ProcessPendingClasses(/*from_kernel=*/true)) {
+      // There is a function _getMainClosure in dart:_builtin that returns the
+      // main procedure.  Since the platform libraries are compiled before the
+      // program script, this function might need to be patched here.
+
+      // If there is no main method then we have compiled a partial Kernel file
+      // and do not need to patch here.
       CanonicalName* main = program_->main_method();
       if (main == NULL) {
         return dart::Library::Handle(Z);
       }
 
+      // If the builtin library is not set in the object store, then we are
+      // bootstrapping and do not need to patch here.
+      dart::Library& builtin_library =
+          dart::Library::Handle(Z, I->object_store()->builtin_library());
+      if (builtin_library.IsNull()) {
+        return dart::Library::Handle(Z);
+      }
+
       CanonicalName* main_library = H.EnclosingName(main);
       dart::Library& library = LookupLibrary(main_library);
       // Sanity check that we can find the main entrypoint.
       Object& main_obj = Object::Handle(
           Z, library.LookupObjectAllowPrivate(H.DartSymbol("main")));
       ASSERT(!main_obj.IsNull());
 
-      // There is a function _getMainClosure in dart:_builtin that returns the
-      // main procedure.  Since the platform libraries are compiled before the
-      // program script, this function is patched here.
-      //
-      // TODO(kmillikin): we are leaking the function body.  Find a way to
-      // deallocate it.
-      dart::Library& builtin_library =
-          dart::Library::Handle(Z, I->object_store()->builtin_library());
       Function& to_patch = Function::Handle(
           Z, builtin_library.LookupFunctionAllowPrivate(
                  dart::String::Handle(dart::String::New("_getMainClosure"))));
 
-      // We will handle the StaticGet specially and will not use the name.
       Procedure* procedure =
           reinterpret_cast<Procedure*>(to_patch.kernel_function());
-      procedure->function()->set_body(new ReturnStatement(new StaticGet(NULL)));
-
+      // If dart:_builtin was not compiled from Kernel at all or if it was
+      // linked with a script, it does not need to be patched.
+      if ((procedure != NULL) && (procedure->function()->body() == NULL)) {
+        // We will handle the StaticGet specially and will not use the name.
+        //
+        // TODO(kmillikin): we are leaking the function body.  Find a way to
+        // deallocate it.
+        procedure->function()->set_body(
+            new ReturnStatement(new StaticGet(NULL)));
+      }
       return library;
     }
   }
 
   // Either class finalization failed or we caught a compile error.
   // In both cases sticky error would be set.
   Error& error = Error::Handle(Z);
   error = thread_->sticky_error();
   thread_->clear_sticky_error();
   return error;
@@ skipping 706 matching lines @@
   initializer_fun.set_is_debuggable(false);
   initializer_fun.set_is_reflectable(false);
   initializer_fun.set_is_inlinable(false);
   return new (zone) ParsedFunction(thread, initializer_fun);
 }
 
 
 }  // namespace kernel
 }  // namespace dart
 #endif  // !defined(DART_PRECOMPILED_RUNTIME)