After some careful investigation of Browser5 test, I found that having
browser.evluate() trigger SWT listeners via readAndDispatch() can 
trigger undesired SWT listeners. This can lead to unexpected behaviour
across platforms where SWT listeners fire unexpectedly.

This fix makes evaluate() logic only process Gtk events and not SWT
listeners.

With this fix Browser5 test works. In fact all Browser jUnits (except 1
that is skipped) now pass.

Tests:
- AllBrowserTests Webkit2 OK
- ChildEclipse Webkit2 OK

Please note, dependent patch must be merged first.

Change-Id: I5aee754e4a8d90b2b1f7c1d6e00ac0a9dc2f360e
Task-Url: https://bugs.eclipse.org/bugs/show_bug.cgi?id=512001
Signed-off-by: Leo Ufimtsev <lufimtse@redhat.com>