Verify that source string matches serialized code.

src/objects-inl.h

Index: src/objects-inl.h
diff --git a/src/objects-inl.h b/src/objects-inl.h
index b750b71a88b75ba5395c4913b7a95c4a5cd04416..dc235df84561a17b7f5c8d560eec34f4bd31bf91 100644
--- a/src/objects-inl.h
+++ b/src/objects-inl.h
@@ -6562,6 +6562,35 @@ uint32_t StringHasher::HashSequentialString(const schar* chars,
 }
 
 
+uint32_t IteratingStringHasher::Hash(String* string, uint32_t seed) {
+  IteratingStringHasher hasher(string->length(), seed);
+  // Nothing to do.
+  if (hasher.has_trivial_hash()) return hasher.GetHashField();
+  ConsString* cons_string = String::VisitFlat(&hasher, string);
+  // The string was flat.
+  if (cons_string == NULL) return hasher.GetHashField();
+  // This is a ConsString, iterate across it.
+  ConsStringIteratorOp op(cons_string);
+  int offset;
+  while (NULL != (string = op.Next(&offset))) {
+    String::VisitFlat(&hasher, string, offset);
+  }
+  return hasher.GetHashField();
+}
+
+
+void IteratingStringHasher::VisitOneByteString(const uint8_t* chars,
+                                               int length) {
+  AddCharacters(chars, length);
+}
+
+
+void IteratingStringHasher::VisitTwoByteString(const uint16_t* chars,
+                                               int length) {
+  AddCharacters(chars, length);
+}
+
+
 bool Name::AsArrayIndex(uint32_t* index) {
   return IsString() && String::cast(this)->AsArrayIndex(index);
 }