[xtext][validation] Propagate cancellation

see https://bugs.eclipse.org/bugs/show_bug.cgi?id=454776

Change-Id: I74f53817f1e8fc6498af4b62f93fb26b2e9e4a88
[xtend][compiler] Fixed compiler problem with anon classes

see https://bugs.eclipse.org/bugs/show_bug.cgi?id=453821

Change-Id: I33d24179835f2e0b99199e8c29a3001d850fec1a