Fix bug in r6930 and r6933...

src/x64/full-codegen-x64.cc

Index: src/x64/full-codegen-x64.cc
===================================================================
--- src/x64/full-codegen-x64.cc	(revision 6935)
+++ src/x64/full-codegen-x64.cc	(working copy)
@@ -854,16 +854,14 @@
   ForIn loop_statement(this, stmt);
   increment_loop_depth();
 
-  // Load null value as it is used several times below.
-  Register null_value = rdi;
-  __ LoadRoot(null_value, Heap::kNullValueRootIndex);
-
   // Get the object to enumerate over. Both SpiderMonkey and JSC
   // ignore null and undefined in contrast to the specification; see
   // ECMA-262 section 12.6.4.
   VisitForAccumulatorValue(stmt->enumerable());
   __ CompareRoot(rax, Heap::kUndefinedValueRootIndex);
   __ j(equal, &exit);
+  Register null_value = rdi;
+  __ LoadRoot(null_value, Heap::kNullValueRootIndex);
   __ cmpq(rax, null_value);
   __ j(equal, &exit);