Optimizing: Tag arena allocations in code generators.

And completely remove the deprecated GrowableArray.

Replace GrowableArray with ArenaVector in code generators
and related classes and tag arena allocations.

Label arrays use direct allocations from ArenaAllocator
because Label is non-copyable and non-movable and as such
cannot be really held in a container. The GrowableArray
never actually constructed them, instead relying on the
zero-initialized storage from the arena allocator to be
correct. We now actually construct the labels.

Also avoid StackMapStream::ComputeDexRegisterMapSize() being
passed null references, even though unused.

Change-Id: I26a46fdd406b23a3969300a67739d55528df8bf4
diff --git a/compiler/optimizing/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index 1d98789..111112e 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -299,11 +299,11 @@
   void MarkGCCard(Register temp, Register card, Register object, Register value, bool can_be_null);
 
   Label* GetLabelOf(HBasicBlock* block) const {
-    return CommonGetLabelOf<Label>(block_labels_.GetRawStorage(), block);
+    return CommonGetLabelOf<Label>(block_labels_, block);
   }
 
   void Initialize() OVERRIDE {
-    block_labels_.SetSize(GetGraph()->GetBlocks().size());
+    block_labels_ = CommonInitializeLabels<Label>();
   }
 
   void Finalize(CodeAllocator* allocator) OVERRIDE;
@@ -335,7 +335,7 @@
   Literal* DeduplicateMethodCodeLiteral(MethodReference target_method);
 
   // Labels for each block that will be compiled.
-  GrowableArray<Label> block_labels_;
+  Label* block_labels_;  // Indexed by block id.
   Label frame_entry_label_;
   LocationsBuilderARM location_builder_;
   InstructionCodeGeneratorARM instruction_visitor_;