Eliminate JsonParser::factory_ member.

This is always equal to isolate_ (so getting it from the isolate is totally
free), and this makes the code slightly smaller while avoiding a few loads
and stores here and there.

Change-Id: Ib648cd0a1f6ea7cbb73a0188ec92cd091ce34792
Reviewed-on: https://chromium-review.googlesource.com/794046Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Jeremy Roman <jbroman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49758}

src/json-parser.cc

@@ -107,7 +107,6 @@ JsonParser<seq_one_byte>::JsonParser(Isolate* isolate, Handle<String> source)
     : source_(source),
       source_length_(source->length()),
       isolate_(isolate),
-      factory_(isolate_->factory()),
       zone_(isolate_->allocator(), ZONE_NAME),
       object_constructor_(isolate_->native_context()->object_function(),
                           isolate_),

src/json-parser.h

@@ -135,7 +135,7 @@ class JsonParser BASE_EMBEDDED {
   }
 
   inline Isolate* isolate() { return isolate_; }
-  inline Factory* factory() { return factory_; }
+  inline Factory* factory() { return isolate_->factory(); }
   inline Handle<JSFunction> object_constructor() { return object_constructor_; }
 
   static const int kInitialSpecialStringLength = 32;
@@ -153,7 +153,6 @@ class JsonParser BASE_EMBEDDED {
 
   PretenureFlag pretenure_;
   Isolate* isolate_;
-  Factory* factory_;
   Zone zone_;
   Handle<JSFunction> object_constructor_;
   uc32 c0_;