[Tests] Do not dispose SWT system colors

This is probably the reason for the following (on first sight unrelated)
test failure:
java.lang.IllegalArgumentException: Argument not valid
	at org.eclipse.swt.SWT.error(SWT.java:4704)
	at org.eclipse.swt.SWT.error(SWT.java:4638)
	at org.eclipse.swt.SWT.error(SWT.java:4609)
	at org.eclipse.swt.graphics.GC.setForeground(GC.java:3266)
	at org.eclipse.swt.custom.CTabFolderRenderer.drawSelected(CTabFolderRenderer.java:1487)
	at org.eclipse.swt.custom.CTabFolderRenderer.draw(CTabFolderRenderer.java:637)
	at org.eclipse.swt.custom.CTabFolder.onPaint(CTabFolder.java:2085)
    ...
	at org.eclipse.swt.internal.gtk.OS.g_main_context_iteration(Native
Method)
	at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:4446)
	at org.eclipse.swt.tests.junit.Test_org_eclipse_swt_custom_CTabFolder.processEvents(Test_org_eclipse_swt_custom_CTabFolder.java:295)
	at org.eclipse.swt.tests.junit.Test_org_eclipse_swt_custom_CTabFolder.test_chevronAppearanceChanged(Test_org_eclipse_swt_custom_CTabFolder.java:261)

Change-Id: Ie7b8cea8ce273627cca5bac09aead58affdfdc89
Signed-off-by: Paul Pazderski <paul-eclipse@ppazderski.de>
diff --git a/tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Text.java b/tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Text.java
index 2516d92..8522eb5 100644
--- a/tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Text.java
+++ b/tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_widgets_Text.java
@@ -1168,10 +1168,6 @@
 	text.setForeground(white);
 	assertEquals(text.getForeground(), white);
 	assertEquals(text.getBackground(), gray);
-
-	gray.dispose();
-	white.dispose();
-	defaultForeground.dispose();
 }
 
 @Test