Fix PNG stream method name in benchmark (fixes #1672)

* fixes #1672, updated `createSyncPNGStream` to `createPNGStream`

* fix #1672 reflected in changelog

Author: gregzanch

CHANGELOG.md

@@ -12,6 +12,7 @@ project adheres to [Semantic Versioning](http://semver.org/).
 * Added support for  `inverse()` and `invertSelf()` to `DOMMatrix` (#1648)
 ### Fixed
 * Fix Pango logging "expect ugly output" on Windows (#1643)
+* Fix benchmark for createPNGStream (#1672)
 
 2.7.0
 ==================

benchmarks/run.js

@@ -157,7 +157,7 @@ bm('getImageData(0,0,100,100)', function () {
 })
 
 bm('PNGStream 200x200', function (done) {
-  var stream = canvas.createSyncPNGStream()
+  var stream = canvas.createPNGStream()
   stream.on('data', function (chunk) {
     // whatever
   })