Introduce per-isolate assert scopes and API to guard JS execution.

src/mark-compact.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 3028 matching lines @@
   }
 
   return false;
 }
 
 
 void MarkCompactCollector::EvacuateNewSpace() {
   // There are soft limits in the allocation code, designed trigger a mark
   // sweep collection by failing allocations.  But since we are already in
   // a mark-sweep allocation, there is no sense in trying to trigger one.
-  AlwaysAllocateScope scope;
+  AlwaysAllocateScope scope(isolate());
   heap()->CheckNewSpaceExpansionCriteria();
 
   NewSpace* new_space = heap()->new_space();
 
   // Store allocation range before flipping semispaces.
   Address from_bottom = new_space->bottom();
   Address from_top = new_space->top();
 
   // Flip the semispaces.  After flipping, to space is empty, from space has
   // live objects.
@@ skipping 11 matching lines @@
     NewSpacePage* p = it.next();
     survivors_size += DiscoverAndPromoteBlackObjectsOnPage(new_space, p);
   }
 
   heap_->IncrementYoungSurvivorsCounter(survivors_size);
   new_space->set_age_mark(new_space->top());
 }
 
 
 void MarkCompactCollector::EvacuateLiveObjectsFromPage(Page* p) {
-  AlwaysAllocateScope always_allocate;
+  AlwaysAllocateScope always_allocate(isolate());
   PagedSpace* space = static_cast<PagedSpace*>(p->owner());
   ASSERT(p->IsEvacuationCandidate() && !p->WasSwept());
   p->MarkSweptPrecisely();
 
   int offsets[16];
 
   for (MarkBitCellIterator it(p); !it.Done(); it.Advance()) {
     Address cell_base = it.CurrentCellBase();
     MarkBit::CellType* cell = it.CurrentCell();
 
@@ skipping 1421 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal