[458822] Replace call to eAllContents() to retrieve diagram elements

Call DDiagramInternalQuery.getDiagramElements() instead of
eAllContents() to retrieve diagram elements because the query is
performing better.

Bug: 458822
Change-Id: Ic6229a04255d25b2fdeaf42a1908866b4392971b
Signed-off-by: Mickael LANOE <mickael.lanoe@obeo.fr>
1 file changed