Turn dead code elimination into a proper HPhase.

src/hydrogen-dce.h

Index: src/hydrogen-dce.h
diff --git a/src/hydrogen-escape-analysis.h b/src/hydrogen-dce.h
similarity index 79%
copy from src/hydrogen-escape-analysis.h
copy to src/hydrogen-dce.h
index 6ba6e823c54f25f2ef4c45a13c9aedba37cfa566..19749f279a2e1cb632ba5a300033e5a9f038638f 100644
--- a/src/hydrogen-escape-analysis.h
+++ b/src/hydrogen-dce.h
@@ -25,33 +25,32 @@
 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
-#ifndef V8_HYDROGEN_ESCAPE_ANALYSIS_H_
-#define V8_HYDROGEN_ESCAPE_ANALYSIS_H_
+#ifndef V8_HYDROGEN_DCE_H_
+#define V8_HYDROGEN_DCE_H_
 
-#include "allocation.h"
 #include "hydrogen.h"
 
 namespace v8 {
 namespace internal {
 
 
-class HEscapeAnalysisPhase : public HPhase {
+class HDeadCodeEliminationPhase : public HPhase {
  public:
-  explicit HEscapeAnalysisPhase(HGraph* graph)
-      : HPhase("H_Escape analysis", graph), captured_(0, zone()) { }
+  explicit HDeadCodeEliminationPhase(HGraph* graph)
+      : HPhase("H_Dead code elimination", graph) { }
 
   void Run() {
-    CollectCapturedValues();
+    MarkLiveInstructions();
+    RemoveDeadInstructions();
   }
 
  private:
-  void CollectCapturedValues();
-  void CollectIfNoEscapingUses(HInstruction* instr);
-
-  ZoneList<HValue*> captured_;
+  bool MarkLive(HValue* ref, HValue* instr);
+  void MarkLiveInstructions();
+  void RemoveDeadInstructions();
 };
 
 
 } }  // namespace v8::internal
 
-#endif  // V8_HYDROGEN_ESCAPE_ANALYSIS_H_
+#endif  // V8_HYDROGEN_DCE_H_