Verify that source string matches serialized code.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index e13a90a89515d5ec03b0644b63d27fe669820320..4dfed65489e58eb44b5831357f9711d9a26642e0 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -8854,6 +8854,19 @@ class StringHasher {
 };
 
 
+class IteratingStringHasher : public StringHasher {
+ public:
+  static inline uint32_t Hash(String* string, uint32_t seed);
+  inline void VisitOneByteString(const uint8_t* chars, int length);
+  inline void VisitTwoByteString(const uint16_t* chars, int length);
+
+ private:
+  inline IteratingStringHasher(int len, uint32_t seed)
+      : StringHasher(len, seed) {}
+  DISALLOW_COPY_AND_ASSIGN(IteratingStringHasher);
+};
+
+
 // The characteristics of a string are stored in its map.  Retrieving these
 // few bits of information is moderately expensive, involving two memory
 // loads where the second is dependent on the first.  To improve efficiency