Fixed pointer arithmetic in write barrier for large objects when marking progress bar is used.

src/spaces.h

Index: src/spaces.h
diff --git a/src/spaces.h b/src/spaces.h
index c246c944c7e819c420031db9a6e7e9c2333d100f..2e5367aa0ec992eee765a8b4516260c5b8fe7acc 100644
--- a/src/spaces.h
+++ b/src/spaces.h
@@ -506,7 +506,7 @@ class MemoryChunk {
   bool IsLeftOfProgressBar(Object** slot) {
     Address slot_address = reinterpret_cast<Address>(slot);
     ASSERT(slot_address > this->address());
-    return (slot_address - this->address() + kObjectStartOffset) <
+    return (slot_address - (this->address() + kObjectStartOffset)) <
            progress_bar();
   }