Eliminate fake-Isolate workaround from concurrent sweeper.

runtime/vm/pages.cc

 // 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.
 
 #include "vm/pages.h"
 
 #include "platform/assert.h"
 #include "vm/compiler_stats.h"
 #include "vm/gc_marker.h"
 #include "vm/gc_sweeper.h"
@@ skipping 778 matching lines @@
 
   int64_t mid2 = OS::GetCurrentTimeMicros();
   int64_t mid3 = 0;
 
   {
     if (FLAG_verify_before_gc) {
       OS::PrintErr("Verifying before sweeping...");
       heap_->Verify(kAllowMarked);
       OS::PrintErr(" done.\n");
     }
-    GCSweeper sweeper;
+    GCSweeper sweeper(isolate->class_table());
 
     // During stop-the-world phases we should use bulk lock when adding elements
     // to the free list.
     MutexLocker mld(freelist_[HeapPage::kData].mutex());
     MutexLocker mle(freelist_[HeapPage::kExecutable].mutex());
 
     // Large and executable pages are always swept immediately.
     HeapPage* prev_page = NULL;
     HeapPage* page = large_pages_;
     while (page != NULL) {
@@ skipping 307 matching lines @@
     return 0;
   } else {
     ASSERT(total_time >= gc_time);
     int result = static_cast<int>((static_cast<double>(gc_time) /
                                    static_cast<double>(total_time)) * 100);
     return result;
   }
 }
 
 }  // namespace dart