Unroll more StringDictionary lookup probes both for positive and negative dictionary lookups.

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index d57d2be9c3b0d75f2e3dfea15948b9d0ea6aec96..a7041d98439221635db4cedeb1c222e1bbdb1e55 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -65,7 +65,8 @@ namespace internal {
   V(NumberToString)                      \
   V(CEntry)                              \
   V(JSEntry)                             \
-  V(DebuggerStatement)
+  V(DebuggerStatement)                   \
+  V(StringDictionaryNegativeLookup)
 
 // List of code stubs only used on ARM platforms.
 #ifdef V8_TARGET_ARCH_ARM