Refactor handling of test expressions in the graph builder.

src/hydrogen.h

Index: src/hydrogen.h
===================================================================
--- src/hydrogen.h	(revision 8460)
+++ src/hydrogen.h	(working copy)
@@ -579,7 +579,7 @@
  private:
   // Build the shared core part of the translation unpacking a value into
   // control flow.
-  void BuildBranch(HValue* value);
+  void BuildBranch(HValue* value, HControlInstruction* test);
 
   Expression* condition_;
   HBasicBlock* if_true_;
@@ -706,6 +706,8 @@
 
   void Bailout(const char* reason);
 
+  void MaterializeBoolean(HControlInstruction* instr, int join_id);
+
  private:
   // Type of a member function that generates inline code for a native function.
   typedef void (HGraphBuilder::*InlineFunctionGenerator)(CallRuntime* call);