Fix crash during hydrogen trace.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
===================================================================
--- src/hydrogen-instructions.cc	(revision 13157)
+++ src/hydrogen-instructions.cc	(working copy)
@@ -1032,7 +1032,10 @@
 void HJSArrayLength::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" ");
-  typecheck()->PrintNameTo(stream);
+  if (typecheck() != NULL)
+    typecheck()->PrintNameTo(stream);
+  else
+    stream->Add("no_typecheck");
 }
 
 
@@ -1145,7 +1148,10 @@
 void HLoadElements::PrintDataTo(StringStream* stream) {
   value()->PrintNameTo(stream);
   stream->Add(" ");
-  typecheck()->PrintNameTo(stream);
+  if (typecheck() != NULL)
+    typecheck()->PrintNameTo(stream);
+  else
+    stream->Add("no_typecheck");
 }
 
 
@@ -2020,7 +2026,10 @@
     stream->Add("] ");
   }
 
-  dependency()->PrintNameTo(stream);
+  if (dependency() != NULL)
+    dependency()->PrintNameTo(stream);
+  else
+    stream->Add("no_dep");
   if (RequiresHoleCheck()) {
     stream->Add(" check_hole");
   }