small misspelling fixes.

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 2056 matching lines @@
   // and switches to a different marking system.  JS interrupts interfere
   // with the C stack limit check.
   PostponeInterruptsScope postpone(isolate());
 
   bool incremental_marking_overflowed = false;
   IncrementalMarking* incremental_marking = heap_->incremental_marking();
   if (was_marked_incrementally_) {
     // Finalize the incremental marking and check whether we had an overflow.
     // Both markers use grey color to mark overflowed objects so
     // non-incremental marker can deal with them as if overflow
-    // occured during normal marking.
+    // occurred during normal marking.
     // But incremental marker uses a separate marking deque
     // so we have to explicitly copy its overflow state.
     incremental_marking->Finalize();
     incremental_marking_overflowed =
         incremental_marking->marking_deque()->overflowed();
     incremental_marking->marking_deque()->ClearOverflowed();
   } else {
     // Abort any pending incremental activities e.g. incremental sweeping.
     incremental_marking->Abort();
   }
@@ skipping 2045 matching lines @@
   while (buffer != NULL) {
     SlotsBuffer* next_buffer = buffer->next();
     DeallocateBuffer(buffer);
     buffer = next_buffer;
   }
   *buffer_address = NULL;
 }
 
 
 } }  // namespace v8::internal