Disable VirtualLazyTreeViewerTest#testContains() on Mac #1183

The test case
org.eclipse.jface.tests.viewers.VirtualLazyTreeViewerTest.testContains
is randomly failing on Mac. Several other test cases accessing the data
of items in a tree viewer with lazy content provider have been disabled
on Mac due to some issue with the availability of the item data (bug
347491).

Since there is no value in executing this test when the functionality is
known to be broken and thus other related test cases are already
disabled, this change disables the random failing test.

Fixes #1183

tests/org.eclipse.jface.tests/src/org/eclipse/jface/tests/viewers/VirtualLazyTreeViewerTest.java

@@ -48,7 +48,8 @@ protected StructuredViewer createViewer(Composite parent) {
 	@Override
 	public void setUp() {
 		super.setUp();
-		// process events because the content provider uses an asyncExec to set the item count of the tree
+		// process events because the content provider uses an asyncExec to set the item
+		// count of the tree
 		processEvents();
 	}
 
@@ -240,4 +241,16 @@ public void testWorldChanged() {
 		}
 		super.testWorldChanged();
 	}
+
+	@Override
+	public void testContains() {
+		if (disableTestsBug347491) {
+			return;
+		}
+		if (setDataCalls == 0) {
+			System.err.println("SWT.SetData is not received. Cancelled test " + testName.getMethodName());
+			return;
+		}
+		super.testContains();
+	}
 }