Bug 22467 TextEdits: replace != delete + insert
see TextBufferTest.testReplaceAndInsert1
org.eclipse.jdt.ui.tests/ui/org/eclipse/jdt/ui/tests/core/TextBufferTest.java
SimpleTextEdit e1= SimpleTextEdit.createInsert(2, "yy");
		SimpleTextEdit e2= SimpleTextEdit.createReplace(2, 3, "3456");
		fEditor.add(e1);
		fEditor.add(e2);
		assertTrue(fEditor.canPerformEdits());
		UndoMemento undo= fEditor.performEdits(null);
		assert(e1.getTextRange(), 2, 2);
		assert(e2.getTextRange(), 4, 4);
		assertEquals("Buffer content", "01yy345656789", fBuffer.getContent());
		doUndo(undo);
		assert(e1.getTextRange(), 2, 0);
		assert(e2.getTextRange(), 2, 3);
	}
	
	public void testInsert2() throws Exception {
		
		SimpleTextEdit e1= SimpleTextEdit.createInsert(2, "yy");
		SimpleTextEdit e2= SimpleTextEdit.createInsert(2, "xx");
		fEditor.add(e1);
		fEditor.add(e2);
		assertTrue(fEditor.canPerformEdits());
		UndoMemento undo= fEditor.performEdits(null);
		assert(e1.getTextRange(), 2, 2);
		assert(e2.getTextRange(), 4, 2);
		assertEquals("Buffer content", "01yyxx23456789", fBuffer.getContent());
		doUndo(undo);
		assert(e1.getTextRange(), 2, 0);
		assert(e2.getTextRange(), 2, 0);
	}