Clean up Scoped-/ArenaAlocator array allocations.

Change-Id: Id718f8a4450adf1608306286fa4e6b9194022532
diff --git a/compiler/dex/quick/ralloc_util.cc b/compiler/dex/quick/ralloc_util.cc
index 8efafb2..67fb804 100644
--- a/compiler/dex/quick/ralloc_util.cc
+++ b/compiler/dex/quick/ralloc_util.cc
@@ -1191,8 +1191,7 @@
   int num_regs = mir_graph_->GetNumOfCodeAndTempVRs();
   const int promotion_threshold = 1;
   // Allocate the promotion map - one entry for each Dalvik vReg or compiler temp
-  promotion_map_ = static_cast<PromotionMap*>
-      (arena_->Alloc(num_regs * sizeof(promotion_map_[0]), kArenaAllocRegAlloc));
+  promotion_map_ = arena_->AllocArray<PromotionMap>(num_regs, kArenaAllocRegAlloc);
 
   // Allow target code to add any special registers
   AdjustSpillMask();
@@ -1210,12 +1209,8 @@
    */
   size_t core_reg_count_size = WideGPRsAreAliases() ? num_regs : num_regs * 2;
   size_t fp_reg_count_size = WideFPRsAreAliases() ? num_regs : num_regs * 2;
-  RefCounts *core_regs =
-      static_cast<RefCounts*>(arena_->Alloc(sizeof(RefCounts) * core_reg_count_size,
-                                            kArenaAllocRegAlloc));
-  RefCounts *fp_regs =
-      static_cast<RefCounts *>(arena_->Alloc(sizeof(RefCounts) * fp_reg_count_size,
-                                             kArenaAllocRegAlloc));
+  RefCounts *core_regs = arena_->AllocArray<RefCounts>(core_reg_count_size, kArenaAllocRegAlloc);
+  RefCounts *fp_regs = arena_->AllocArray<RefCounts>(fp_reg_count_size, kArenaAllocRegAlloc);
   // Set ssa names for original Dalvik registers
   for (int i = 0; i < num_regs; i++) {
     core_regs[i].s_reg = fp_regs[i].s_reg = i;