Add a parent environment to HEnvironment.

This code has no functionality change. It adds a placeholder
for chaining inlined frames.

Change-Id: I5ec57335af76ee406052345b947aad98a6a4423a
diff --git a/compiler/optimizing/gvn_test.cc b/compiler/optimizing/gvn_test.cc
index a81d49a..c3ce7e1 100644
--- a/compiler/optimizing/gvn_test.cc
+++ b/compiler/optimizing/gvn_test.cc
@@ -29,7 +29,7 @@
   ArenaPool pool;
   ArenaAllocator allocator(&pool);
 
-  HGraph* graph = new (&allocator) HGraph(&allocator);
+  HGraph* graph = CreateGraph(&allocator);
   HBasicBlock* entry = new (&allocator) HBasicBlock(graph);
   graph->AddBlock(entry);
   graph->SetEntryBlock(entry);
@@ -78,7 +78,7 @@
   ArenaPool pool;
   ArenaAllocator allocator(&pool);
 
-  HGraph* graph = new (&allocator) HGraph(&allocator);
+  HGraph* graph = CreateGraph(&allocator);
   HBasicBlock* entry = new (&allocator) HBasicBlock(graph);
   graph->AddBlock(entry);
   graph->SetEntryBlock(entry);
@@ -133,7 +133,7 @@
   ArenaPool pool;
   ArenaAllocator allocator(&pool);
 
-  HGraph* graph = new (&allocator) HGraph(&allocator);
+  HGraph* graph = CreateGraph(&allocator);
   HBasicBlock* entry = new (&allocator) HBasicBlock(graph);
   graph->AddBlock(entry);
   graph->SetEntryBlock(entry);
@@ -220,7 +220,7 @@
   ArenaPool pool;
   ArenaAllocator allocator(&pool);
 
-  HGraph* graph = new (&allocator) HGraph(&allocator);
+  HGraph* graph = CreateGraph(&allocator);
   HBasicBlock* entry = new (&allocator) HBasicBlock(graph);
   graph->AddBlock(entry);
   graph->SetEntryBlock(entry);