Clean up the Result class. Reduce the size of Result from four words...

src/compiler.h

Index: src/compiler.h
===================================================================
--- src/compiler.h	(revision 1960)
+++ src/compiler.h	(working copy)
@@ -79,7 +79,10 @@
  public:
   explicit CompilationZoneScope(ZoneScopeMode mode) : ZoneScope(mode) { }
   virtual ~CompilationZoneScope() {
-    if (ShouldDeleteOnExit()) FrameElement::ClearConstantList();
+    if (ShouldDeleteOnExit()) {
+      FrameElement::ClearConstantList();
+      Result::ClearConstantList();
+    }
   }
 };