benchmark: add benchmark for object properties

Adds a benchmark to compare the speed of property setting/getting in
four cases:
- Dot notation: `obj.prop = value`
- Bracket notation with string: `obj['prop'] = value`
- Bracket notation with string variable: `obj[prop] = value`
- Bracket notation with Symbol variable: `obj[sym] = value`
PR-URL: #10949
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

Author: targos

benchmark/misc/object-property-bench.js

@@ -0,0 +1,81 @@
+'use strict';
+
+constcommon=require('../common.js');
+
+constbench=common.createBenchmark(main,{
+method: ['property','string','variable','symbol'],
+millions: [1000]
+});
+
+functionrunProperty(n){
+constobject={};
+vari=0;
+bench.start();
+for(;i<n;i++){
+object.p1=21;
+object.p2=21;
+object.p1+=object.p2;
+}
+bench.end(n/1e6);
+}
+
+functionrunString(n){
+constobject={};
+vari=0;
+bench.start();
+for(;i<n;i++){
+object['p1']=21;
+object['p2']=21;
+object['p1']+=object['p2'];
+}
+bench.end(n/1e6);
+}
+
+functionrunVariable(n){
+constobject={};
+constvar1='p1';
+constvar2='p2';
+vari=0;
+bench.start();
+for(;i<n;i++){
+object[var1]=21;
+object[var2]=21;
+object[var1]+=object[var2];
+}
+bench.end(n/1e6);
+}
+
+functionrunSymbol(n){
+constobject={};
+constsymbol1=Symbol('p1');
+constsymbol2=Symbol('p2');
+vari=0;
+bench.start();
+for(;i<n;i++){
+object[symbol1]=21;
+object[symbol2]=21;
+object[symbol1]+=object[symbol2];
+}
+bench.end(n/1e6);
+}
+
+functionmain(conf){
+constn=+conf.millions*1e6;
+
+switch(conf.method){
+case'property':
+runProperty(n);
+break;
+case'string':
+runString(n);
+break;
+case'variable':
+runVariable(n);
+break;
+case'symbol':
+runSymbol(n);
+break;
+default:
+thrownewError('Unexpected method');
+}
+}