Introduce new API to expose external string resource regardless of encoding.

src/api.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4071 matching lines @@
   if (i::StringShape(*str).IsExternalTwoByte()) {
     const void* resource =
         i::Handle<i::ExternalTwoByteString>::cast(str)->resource();
     expected = reinterpret_cast<const ExternalStringResource*>(resource);
   } else {
     expected = NULL;
   }
   CHECK_EQ(expected, value);
 }
 
+void v8::String::VerifyExternalStringResourceBase(
+    v8::String::ExternalStringResourceBase* value,
+    Encoding encoding) const {
+  i::Handle<i::String> str = Utils::OpenHandle(this);
+  const v8::String::ExternalStringResourceBase* expected;
+  Encoding expectedEncoding;
+  if (i::StringShape(*str).IsExternalAscii()) {
+    const void* resource =
+        i::Handle<i::ExternalAsciiString>::cast(str)->resource();
+    expected = reinterpret_cast<const ExternalStringResourceBase*>(resource);
+    expectedEncoding = ASCII_ENCODING;
+  } else if (i::StringShape(*str).IsExternalTwoByte()) {
+    const void* resource =
+        i::Handle<i::ExternalTwoByteString>::cast(str)->resource();
+    expected = reinterpret_cast<const ExternalStringResourceBase*>(resource);
+    expectedEncoding = TWO_BYTE_ENCODING;
+  } else {
+    expected = NULL;
+    expectedEncoding = str->IsAsciiRepresentation() ? ASCII_ENCODING
+                                                    : TWO_BYTE_ENCODING;
+  }
+  CHECK_EQ(expected, value);
+  CHECK_EQ(expectedEncoding, encoding);
+}
 
 const v8::String::ExternalAsciiStringResource*
       v8::String::GetExternalAsciiStringResource() const {
   i::Handle<i::String> str = Utils::OpenHandle(this);
   if (IsDeadCheck(str->GetIsolate(),
                   "v8::String::GetExternalAsciiStringResource()")) {
     return NULL;
   }
   if (i::StringShape(*str).IsExternalAscii()) {
     const void* resource =
@@ skipping 2452 matching lines @@
 
   v->VisitPointers(blocks_.first(), first_block_limit_);
 
   for (int i = 1; i < blocks_.length(); i++) {
     v->VisitPointers(blocks_[i], &blocks_[i][kHandleBlockSize]);
   }
 }
 
 
 } }  // namespace v8::internal