Bug 560259 - NPE in
InlinedAnnotationSupport$UpdateStylesWidth.applyTextPresentation

Added null check for ISourceViewer.getAnnotationModel() return value
that allowed to be null.

Change-Id: Ib0ffbbd3cdec18dc24a0c9de4a8c32ab8f24abe7
Signed-off-by: Andrey Loskutov <loskutov@gmx.de>