Bug 1448089 followup, remove now-unused variable to fix a CLOSED TREE.

--HG--
extra : amend_source : 001ccd09e2af56c45e01e9057a64fb6cd23fe874
extra : histedit_source : 32a294be08fe4fd4082f9591c2582e2c14386841

js/src/jit/MIRGraph.cpp

@@ -1156,8 +1156,6 @@ MBasicBlock::addPredecessorSameInputsAs(MBasicBlock* pred, MBasicBlock* existing
     MOZ_ASSERT(pred->hasLastIns());
     MOZ_ASSERT(!pred->successorWithPhis());
 
-    AutoEnterOOMUnsafeRegion oomUnsafe;
-
     if (!phisEmpty()) {
         size_t existingPosition = indexForPredecessor(existingPred);
         for (MPhiIterator iter = phisBegin(); iter != phisEnd(); iter++) {