[heap] Fix {InternalizeString} for char vectors

Even though {Factory::InternalizeString} was declared as a template,
only two instantiations exists: uint8_t and uint16_t. Using any other
type leads to link-time errors, which is inconvenient.

This CL implements the two instantiations explicitly, and provides a
third implementation taking a {Vector<const char>}. This will be used
after the next CL, which changes {StaticCharVector} to actually return a
{Vector<const char>}.

This also avoid the cumbersome template exports.

R=leszeks@chromium.org

Bug: v8:10426
Change-Id: I3f669fae2c711ade6f5a087e59210ad457423a66
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2152837
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67207}

src/heap/factory.cc

@@ -530,19 +530,19 @@ Handle<String> Factory::InternalizeUtf8String(
       Vector<const uc16>(buffer.get(), decoder.utf16_length()));
 }
 
-template <typename Char>
-Handle<String> Factory::InternalizeString(const Vector<const Char>& string,
+Handle<String> Factory::InternalizeString(Vector<const uint8_t> string,
                                           bool convert_encoding) {
-  SequentialStringKey<Char> key(string, HashSeed(isolate()), convert_encoding);
+  SequentialStringKey<uint8_t> key(string, HashSeed(isolate()),
+                                   convert_encoding);
   return InternalizeStringWithKey(&key);
 }
 
-template EXPORT_TEMPLATE_DEFINE(V8_EXPORT_PRIVATE)
-    Handle<String> Factory::InternalizeString(
-        const Vector<const uint8_t>& string, bool convert_encoding);
-template EXPORT_TEMPLATE_DEFINE(V8_EXPORT_PRIVATE)
-    Handle<String> Factory::InternalizeString(
-        const Vector<const uint16_t>& string, bool convert_encoding);
+Handle<String> Factory::InternalizeString(Vector<const uint16_t> string,
+                                          bool convert_encoding) {
+  SequentialStringKey<uint16_t> key(string, HashSeed(isolate()),
+                                    convert_encoding);
+  return InternalizeStringWithKey(&key);
+}
 
 template <typename SeqString>
 Handle<String> Factory::InternalizeString(Handle<SeqString> string, int from,

src/heap/factory.h

@@ -184,10 +184,14 @@ class V8_EXPORT_PRIVATE Factory : public FactoryBase<Factory> {
     return InternalizeUtf8String(CStrVector(str));
   }
 
-  template <typename Char>
-  EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE)
-  Handle<String> InternalizeString(const Vector<const Char>& str,
+  Handle<String> InternalizeString(Vector<const uint8_t> str,
                                    bool convert_encoding = false);
+  Handle<String> InternalizeString(Vector<const uint16_t> str,
+                                   bool convert_encoding = false);
+  Handle<String> InternalizeString(Vector<const char> str,
+                                   bool convert_encoding = false) {
+    return InternalizeString(Vector<const uint8_t>::cast(str));
+  }
 
   template <typename SeqString>
   Handle<String> InternalizeString(Handle<SeqString>, int from, int length,