Remove Utf8InputBuffer

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index bd8de1756debecfec17cd404c992cf8d1aaaa543..83a05ade808f32d32ad08889741182da50bbddf8 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -6934,9 +6934,10 @@ class StringHasher {
                                               int length,
                                               uint32_t seed);
 
-  static uint32_t ComputeHashField(unibrow::CharacterStream* buffer,
-                                   int length,
-                                   uint32_t seed);
+  // Reads all the data, even for long strings and computes the utf16 length.
+  static uint32_t ComputeUtf8Hash(Vector<const char> chars,
+                                  uint32_t seed,
+                                  int* utf16_length_out);
 
   // Calculated hash value for a string consisting of 1 to
   // String::kMaxArrayIndexSize digits with no leading zeros (except "0").