MIPS: Fix LStoreKeyed error when tracing instruction.

Port r14951 (01dbfe2)

Original commit message:
LStoreKeyed can have a NULL value(), when we recognize we are storing a constant
hole value.

BUG=

Review URL: https://codereview.chromium.org/16171019
Patch from Balazs Kilvady <kilvadyb@homejinni.com>.

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@14959 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/mips/lithium-mips.cc

@@ -409,7 +409,14 @@ void LStoreKeyed::PrintDataTo(StringStream* stream) {
   } else {
     stream->Add("] <- ");
   }
-  value()->PrintTo(stream);
+
+  if (value() == NULL) {
+    ASSERT(hydrogen()->IsConstantHoleStore() &&
+           hydrogen()->value()->representation().IsDouble());
+    stream->Add("<the hole(nan)>");
+  } else {
+    value()->PrintTo(stream);
+  }
 }