Complete the switch to ServiceObject

runtime/platform/json.h

Index: runtime/platform/json.h
diff --git a/runtime/platform/json.h b/runtime/platform/json.h
index 36c7d5d123b3f1812a416efd409d4438d0590969..f1b6feaa3f7eb8d295504d3077cc45e415a2ace1 100644
--- a/runtime/platform/json.h
+++ b/runtime/platform/json.h
@@ -130,6 +130,7 @@ class TextBuffer : ValueObject {
   void AddEscapedChar(uint32_t ch);
   void AddString(const char* s);
   void AddEscapedString(const char* s);
+  void AddEscapedUTF8String(const char* s);
 
   void Clear();
 
@@ -141,6 +142,8 @@ class TextBuffer : ValueObject {
   const char* Steal();
 
  private:
+  static uint32_t Utf8Decode(const uint8_t* s, intptr_t s_len, uint32_t* ch);
+
   void EnsureCapacity(intptr_t len);
   char* buf_;
   intptr_t buf_size_;