Revert "Do not create 4-byte sequences in `ConvertUtf16ToModifiedUtf8()`"

This reverts commit e0a4f373dc4a738a2f26965a67d31239cbbd4f6a.

Reason for revert: DroidMonitor-triggered revert due to breakage https://android-build.googleplex.com/builds/tests/view?invocationId=I44000009917256156&testResultId=TR23027520914949881, bug b/193363191

Bug: 193363191
Change-Id: I2e7fe6de3f63864b58729d2c76e9ab5c95aa7983
diff --git a/test/906-iterate-heap/iterate_heap.cc b/test/906-iterate-heap/iterate_heap.cc
index cc941d8..521f9a6 100644
--- a/test/906-iterate-heap/iterate_heap.cc
+++ b/test/906-iterate-heap/iterate_heap.cc
@@ -198,7 +198,7 @@
                                             void* user_data) {
       FindStringCallbacks* p = reinterpret_cast<FindStringCallbacks*>(user_data);
       if (*tag_ptr == p->tag_to_find) {
-        size_t utf_byte_count = ti::CountModifiedUtf8Bytes(value, value_length);
+        size_t utf_byte_count = ti::CountUtf8Bytes(value, value_length);
         std::unique_ptr<char[]> mod_utf(new char[utf_byte_count + 1]);
         memset(mod_utf.get(), 0, utf_byte_count + 1);
         ti::ConvertUtf16ToModifiedUtf8(mod_utf.get(), utf_byte_count, value, value_length);