Works fine for me when pasted into a page with page template ‘Full Width’. I was not sure what you meant when you say it does not work. I suggest you wrap the googlemap shortcode in a [segment] shortcode to constrain its width to 1140px like below –
[segment][googlemap width="1140" height="300" link="false" src="http://maps.google.com.sg/maps?q=Boon+Siew+S%27Pore+Pte&hl=en&sll=1.307029,103.847762&sspn=0.002639,0.004128&hq=Boon+Siew+S%27Pore+Pte&t=m&z=19"][/segment].
Alternatively, you can increase the size from 1140 to width="1940" height="400" to make it look better on bigger monitors.
To make the maps responsive though, pls look for it in line 313 and make the following change to your {theme directory}/js/main.js file to changed google maps domain name –
$("#content").fitVids({ customSelector: "iframe[src^='http://maps.google.com.sg/']"});