Revert "Ensure that failure to start an isolate all end up in the future."

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 523633ec5c49d1f1abb16b83e6d54c30823d3498..076c369b6a8196f3f005cdae5821be1c48c542ff 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -606,24 +606,14 @@ static bool RunIsolate(uword parameter) {
     Object& result = Object::Handle();
     result = state->ResolveFunction();
     bool is_spawn_uri = state->is_spawn_uri();
-
-    Instance& entryFunc = Instance::Handle(isolate);
     if (result.IsError()) {
-      if (is_spawn_uri) {
-        // Report failure to look up "main" in isolate when we have a
-        // port to reply it to.
-        entryFunc ^= Object::null_instance().raw();
-      } else {
-        StoreError(isolate, result);
-        return false;
-      }
-    } else {
-      ASSERT(result.IsFunction());
-      Function& function = Function::Handle(isolate);
-      function ^= result.raw();
-      function = function.ImplicitClosureFunction();
-      entryFunc ^= function.ImplicitStaticClosure();
+      StoreError(isolate, result);
+      return false;
     }
+    ASSERT(result.IsFunction());
+    Function& func = Function::Handle(isolate);
+    func ^= result.raw();
+    func = func.ImplicitClosureFunction();
 
     // Instead of directly invoking the entry point we call '_startIsolate' with
     // the entry point as argument. The '_startIsolate' function will
@@ -634,7 +624,7 @@ static bool RunIsolate(uword parameter) {
     // "_startIsolate" function can act corresponding to how the isolate was
     // created.
     const Array& args = Array::Handle(Array::New(2));
-    args.SetAt(0, entryFunc);
+    args.SetAt(0, Instance::Handle(func.ImplicitStaticClosure()));
     args.SetAt(1, is_spawn_uri ? Bool::True() : Bool::False());
 
     const Library& lib = Library::Handle(Library::IsolateLibrary());