Remove the --collect-maps flag. Maps should be always collected.

src/heap/mark-compact.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 "src/v8.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
@@ skipping 327 matching lines @@
 
   MarkLiveObjects();
 
   DCHECK(heap_->incremental_marking()->IsStopped());
 
   // ClearNonLiveReferences can deoptimize code in dependent code arrays.
   // Process weak cells before so that weak cells in dependent code
   // arrays are cleared or contain only live code objects.
   ProcessAndClearWeakCells();
 
-  if (FLAG_collect_maps) ClearNonLiveReferences();
+  ClearNonLiveReferences();
 
   ClearWeakCollections();
 
   heap_->set_encountered_weak_cells(Smi::FromInt(0));
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     VerifyMarking(heap_);
   }
 #endif
 
   ClearInvalidStoreAndSlotsBufferEntries();
 
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
     VerifyValidStoreAndSlotsBufferEntries(heap_);
   }
 #endif
 
   SweepSpaces();
 
 #ifdef VERIFY_HEAP
   VerifyWeakEmbeddedObjectsInCode();
-  if (FLAG_collect_maps && FLAG_omit_map_checks_for_leaf_maps) {
+  if (FLAG_omit_map_checks_for_leaf_maps) {
     VerifyOmittedMapChecks();
   }
 #endif
 
   Finish();
 
   if (marking_parity_ == EVEN_MARKING_PARITY) {
     marking_parity_ = ODD_MARKING_PARITY;
   } else {
     DCHECK(marking_parity_ == ODD_MARKING_PARITY);
@@ skipping 4340 matching lines @@
   SlotsBuffer* buffer = *buffer_address;
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 }  // namespace internal
 }  // namespace v8