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

src/ia32/register-allocator-ia32.cc

Index: src/ia32/register-allocator-ia32.cc
===================================================================
--- src/ia32/register-allocator-ia32.cc	(revision 1960)
+++ src/ia32/register-allocator-ia32.cc	(working copy)
@@ -127,7 +127,7 @@
   // register if valid and return an invalid result.
   if (result.is_valid() && !result.reg().is_byte_register()) {
     result.Unuse();
-    return Result(cgen_);
+    return Result();
   }
   return result;
 }