Minor improvements to 458-checker-instruction-simplification.

This follows earlier comments from Roland:
https://android-review.googlesource.com/#/c/140446
  /2/test/458-checker-instruction-simplification/src/Main.java@337
  /2/test/458-checker-instruction-simplification/src/Main.java@465

Change-Id: I255ab74b8885dd8e86bb2c11bba4075fa0eaa183
diff --git a/compiler/optimizing/constant_folding.h b/compiler/optimizing/constant_folding.h
index ac00824..66ff578 100644
--- a/compiler/optimizing/constant_folding.h
+++ b/compiler/optimizing/constant_folding.h
@@ -32,8 +32,8 @@
  */
 class HConstantFolding : public HOptimization {
  public:
-  explicit HConstantFolding(HGraph* graph)
-      : HOptimization(graph, true, kConstantFoldingPassName) {}
+  explicit HConstantFolding(HGraph* graph, const char* name = kConstantFoldingPassName)
+      : HOptimization(graph, true, name) {}
 
   void Run() OVERRIDE;