[JSON] implement indentation in the BasicJsonStringifier and expose via API.

src/string-builder.h

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_STRING_BUILDER_H_
 #define V8_STRING_BUILDER_H_
 
 #include "src/assert-scope.h"
 #include "src/factory.h"
 #include "src/handles.h"
@@ skipping 275 matching lines @@
 
   INLINE(void AppendCString(const char* s)) {
     const uint8_t* u = reinterpret_cast<const uint8_t*>(s);
     if (encoding_ == String::ONE_BYTE_ENCODING) {
       while (*u != '\0') Append<uint8_t, uint8_t>(*(u++));
     } else {
       while (*u != '\0') Append<uint8_t, uc16>(*(u++));
     }
   }
 
+  INLINE(void AppendCString(const uc16* s)) {
+    if (encoding_ == String::ONE_BYTE_ENCODING) {
+      while (*s != '\0') Append<uc16, uint8_t>(*(s++));
+    } else {
+      while (*s != '\0') Append<uc16, uc16>(*(s++));
+    }
+  }
+
   INLINE(bool CurrentPartCanFit(int length)) {
     return part_length_ - current_index_ > length;
   }
 
   void AppendString(Handle<String> string);
 
   MaybeHandle<String> Finish();
 
   // Change encoding to two-byte.
   void ChangeEncoding() {
@@ skipping 122 matching lines @@
     DCHECK_EQ(String::TWO_BYTE_ENCODING, encoding_);
     SeqTwoByteString::cast(*current_part_)
         ->SeqTwoByteStringSet(current_index_++, c);
   }
   if (current_index_ == part_length_) Extend();
 }
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_STRING_BUILDER_H_