Change scanner buffers to not use utf-8.

src/heap.h

Index: src/heap.h
diff --git a/src/heap.h b/src/heap.h
index 463f5f155ff0cac065e83b48846cd7af2ad66dab..3ceefd80bf984e191d33994960fd705e470b5948 100644
--- a/src/heap.h
+++ b/src/heap.h
@@ -431,6 +431,14 @@ class Heap : public AllStatic {
       int chars,
       uint32_t hash_field);
 
+  MUST_USE_RESULT static inline MaybeObject* AllocateAsciiSymbol(
+        Vector<const char> str,
+        uint32_t hash_field);
+
+  MUST_USE_RESULT static inline MaybeObject* AllocateTwoByteSymbol(
+        Vector<const uc16> str,
+        uint32_t hash_field);
+
   MUST_USE_RESULT static MaybeObject* AllocateInternalSymbol(
       unibrow::CharacterStream* buffer, int chars, uint32_t hash_field);
 
@@ -686,6 +694,9 @@ class Heap : public AllStatic {
   // failed.
   // Please note this function does not perform a garbage collection.
   MUST_USE_RESULT static MaybeObject* LookupSymbol(Vector<const char> str);
+  MUST_USE_RESULT static MaybeObject* LookupAsciiSymbol(Vector<const char> str);
+  MUST_USE_RESULT static MaybeObject* LookupTwoByteSymbol(
+      Vector<const uc16> str);
   MUST_USE_RESULT static MaybeObject* LookupAsciiSymbol(const char* str) {
     return LookupSymbol(CStrVector(str));
   }