Remove HTemporary when building the SSA graph.

- They are useless afterwards. If we keep them around, they can
  crash the dump of the graph, where they always assume a previous
  instruction.

- In the call to HTemporary::GetType, check that the previous
  instruction exists.

Change-Id: Ie7bf44d05cb61e3654a69725c1980925580dd3a6
diff --git a/compiler/optimizing/ssa_builder.h b/compiler/optimizing/ssa_builder.h
index 24f5ac5..2207cd6 100644
--- a/compiler/optimizing/ssa_builder.h
+++ b/compiler/optimizing/ssa_builder.h
@@ -51,6 +51,7 @@
   void VisitLoadLocal(HLoadLocal* load);
   void VisitStoreLocal(HStoreLocal* store);
   void VisitInstruction(HInstruction* instruction);
+  void VisitTemporary(HTemporary* instruction);
 
   static HInstruction* GetFloatOrDoubleEquivalent(HInstruction* user,
                                                   HInstruction* instruction,