Test "test_BrowserFunction_callback_stackedCalls" failing on Linux

[fedejeanne]

While providing a fix and a test for #1919 , the test revealed that stacked calls (Java calls JS which calls Java which calls JS .... and so on) are apparently not possible on Linux so the test is currently deactivated for GTK.

This is the test:

• org.eclipse.swt.tests.junit.Test_org_eclipse_swt_browser_Browser.test_BrowserFunction_callback_stackedCalls()

It was added in #2019

Goal

• Find out if this is actually an issue in production and fix it. Edge: Operation timed out on evaluate() #1919 contains information on how to reproduce the issue using Nebula
• Reactivate the test