Eclipse errors about lineStart and lineEnd due to reference to old xsd file

I'm using DockLayoutPanel in ui binder. I want RTL support therefor need to use lineStart and lineEnd instead of east and west. This is working fine, however Eclipse reports errors for these elements.
The reason is that the XML Catalog refers to the following schema file:
http://dl.google.com/gwt/dtd/com.google.gwt.user.client.ui.xsd
This one does not yet contain lineStart and lineEnd.

Sample ui binder:
```


lineStart


west


center


east


lineEnd

```
The error is: cvc-complex-type.2.4.a: Invalid content was found starting with element 'g:lineStart'. One of '{"urn:import:com.google.gwt.user.client.ui":north,
"urn:import:com.google.gwt.user.client.ui":south, "urn:import:com.google.gwt.user.client.ui":west, "urn:import:com.google.gwt.user.client.ui":east,
"urn:import:com.google.gwt.user.client.ui":center}' is expected.
Same for lineEnd.

See also https://github.com/gwtproject/gwt/issues/9524