[json] move json parser and stringifier into own compilation units.

src/runtime/runtime-object.cc

Index: src/runtime/runtime-object.cc
diff --git a/src/runtime/runtime-object.cc b/src/runtime/runtime-object.cc
index 9743d4ab5a4e68615e69b45d19b1eec1b2ccd21d..82f072fcc6404978bf35a55900eb968259d926ad 100644
--- a/src/runtime/runtime-object.cc
+++ b/src/runtime/runtime-object.cc
@@ -8,7 +8,6 @@
 #include "src/bootstrapper.h"
 #include "src/debug/debug.h"
 #include "src/isolate-inl.h"
-#include "src/json-stringifier.h"
 #include "src/messages.h"
 #include "src/property-descriptor.h"
 #include "src/runtime/runtime.h"
@@ -226,16 +225,6 @@ MaybeHandle<Object> Runtime::SetObjectProperty(Isolate* isolate,
   return value;
 }
 
-MaybeHandle<Object> Runtime::BasicJsonStringify(Isolate* isolate,
-                                                Handle<Object> object,
-                                                Handle<String> gap) {
-  return BasicJsonStringifier(isolate, gap).Stringify(object);
-}
-
-MaybeHandle<Object> Runtime::BasicJsonStringifyString(Isolate* isolate,
-                                                      Handle<String> string) {
-  return BasicJsonStringifier::StringifyString(isolate, string);
-}
 
 RUNTIME_FUNCTION(Runtime_GetPrototype) {
   HandleScope scope(isolate);