Revert assertion change from r21933 in Isolate::RunMicrotasks().

src/isolate.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <stdlib.h>
 
 #include "src/v8.h"
 
 #include "src/ast.h"
 #include "src/bootstrapper.h"
@@ skipping 2274 matching lines @@
     queue = FixedArray::CopySize(queue, num_tasks * 2);
     heap()->set_microtask_queue(*queue);
   }
   ASSERT(queue->get(num_tasks)->IsUndefined());
   queue->set(num_tasks, *microtask);
   set_pending_microtask_count(num_tasks + 1);
 }
 
 
 void Isolate::RunMicrotasks() {
-  // In some mjsunit tests %RunMicrotasks is called explicitly, violating
-  // this assertion.  Therefore we also check for --allow-natives-syntax.
-  ASSERT(FLAG_allow_natives_syntax ||
-         handle_scope_implementer()->CallDepthIsZero());
+  // %RunMicrotasks may be called in mjsunit tests, which violates
+  // this assertion, hence the check for --allow-natives-syntax.
+  // TODO(adamk): However, this also fails some layout tests.
+  //
+  // ASSERT(FLAG_allow_natives_syntax ||
+  //        handle_scope_implementer()->CallDepthIsZero());
 
   // Increase call depth to prevent recursive callbacks.
   v8::Isolate::SuppressMicrotaskExecutionScope suppress(
       reinterpret_cast<v8::Isolate*>(this));
 
   while (pending_microtask_count() > 0) {
     HandleScope scope(this);
     int num_tasks = pending_microtask_count();
     Handle<FixedArray> queue(heap()->microtask_queue(), this);
     ASSERT(num_tasks <= queue->length());
@@ skipping 53 matching lines @@
   // The simulator uses a separate JS stack.
   Address jssp_address = Simulator::current(isolate_)->get_sp();
   uintptr_t jssp = reinterpret_cast<uintptr_t>(jssp_address);
   if (jssp < stack_guard->real_jslimit()) return true;
 #endif  // USE_SIMULATOR
   return reinterpret_cast<uintptr_t>(this) < stack_guard->real_climit();
 }
 
 
 } }  // namespace v8::internal