Replace the use CharacterStreams in Heap::AllocateSymbolInternal and String::ComputeHash

src/heap-inl.h

Index: src/heap-inl.h
diff --git a/src/heap-inl.h b/src/heap-inl.h
index e5f290086fe06920ecf13598d115b57652641d0d..f28324261841aea9aebb43e6446d8371049b70a9 100644
--- a/src/heap-inl.h
+++ b/src/heap-inl.h
@@ -101,9 +101,9 @@ MaybeObject* Heap::AllocateStringFromUtf8(Vector<const char> str,
 MaybeObject* Heap::AllocateSymbol(Vector<const char> str,
                                   int chars,
                                   uint32_t hash_field) {
-  unibrow::Utf8InputBuffer<> buffer(str.start(),
-                                    static_cast<unsigned>(str.length()));
-  return AllocateInternalSymbol(&buffer, chars, hash_field);
+  // Must be ascii.
+  if (chars == str.length()) return AllocateAsciiSymbol(str, hash_field);

[Yang, 2012/12/17 14:30:34]

Maybe we could encapsulate this logic by replacing the if-condition with
something like AllocateInternalSymbolHelper::IsOneByte(str, chars) and make sure
this gets inlined.

+  return AllocateInternalSymbol(str, chars, hash_field);
 }