Developers working on WebKit announced late last week that the newest build of the browser engine, which powers both Apple's Safari and Google's Chrome, has aced all of the requirements of an important Web standards test.

"WebKit is the first browser engine to fully pass Acid3," said developer Maciej Stachowiak in a post to the WebKit blog.

The claim was a follow-up to last March's boast by WebKit developers that the browsing engine had scored 100 out of a possible 100 in the Acid3 test. The test, which was approved last March by the Web Standards Project, is designed to check how closely a browser follows certain standards, particularly specifications for Web 2.0 applications, as well as standards related to the DOM (Document Object Model), CSS2 (Cascading Style Sheets) and SVG (Scalable Vector Graphics).

Last Thursday, however, Stachowiak said that the newest builds also met Acid3's "smooth animation" requirement, something it had failed to do in March, by completing each test in under .033 milliseconds. When a browser finishes each test in that time or less, Acid3 shows the message "No JS [JavaScript] errors and no timing issues" in a pop-up window.

WebKit provides the core engine for not only Safari, but since early this month, also Google's Chrome . Google's browser, however, relies on a version of WebKit older than the one touted by Stachowiak.

Computerworld tested the newest WebKit, build r36882, in a virtual machine running Windows XP SP3 on an iMac powered by an Intel 2.4GHz Core 2 Duo processor. Although WebKit scored a perfect 100, it could not complete all tests in the required time in the virtual machine; one test repeatedly failed to meet the 0.33 millisecond cut-off.

However, when the most recent Mac OS X WebKit, build r37012, was tested on the same machine, it scored 100 and finished each test under the 0.33ms mark, confirming Stachowiak's claim.

Computerworld's tests also confirmed his statement that no other major browser could match WebKit's Acid3 score. In the Windows XP SP3 virtual machine, all production and preview versions -- the latter indicated by build numbers or status in parenthesis -- scored less than 90 on the test.