I tried using Pulse to install GWT Designer from the Pulse catalog on a 3.4 based profile and I get a resolution error. Working for Pulse I can look a little deeper at the issue and it seems a recent release has a few changes in the features.
First for http://dl.google.com/eclipse/plugin/3.4 it looks like the feature IDs changed to include the plugin ID. This makes it difficult for us as we will need to change out software listing every time you release code. Also previous releases did not do this.
The bigger issue I cannot fix in our catalog is it seems that http://dl.google.com/eclipse/inst/d2gwt/latest/3.4 is missing a feature from it: org.eclipse.wb.core.xml.feature. Your sites for 3.5 and 3.6 do include this so I hope it can be added to your 3.4 site.
BTW this will not just affect users of Pulse as regular eclipse users will not be able to find that required plugin either.
Thanks
Ray
Pulse Support