No... As far as I know, window.open never replaces the current URL if you do not supply a target name. If you do supply a target and the current window name is the same as the target, it may replace the current document. _blank actually opens a new tab in Chrome.
Using the Developer Tools to evaluate such statements is a bit problematic and does not reflect the world as you may expect.
window.open requires a user gesture (a mouse click, for example) to work, or else the new window is blocked by the popup blocker.
Evaluating using the Developer Tools does not add a user gesture and therefore the window or tab or whatever is not opened.
Also, you cannot really control whether the browser opens a tab or a window as a result of window.open. You can make it open a popup window if you supply some property string as the third argument, but not control whether a full window or a tab will be opened.