Bug 65378 FindOccurencesCUEngine should use ASTProvider
RC1 FindOccurrencesEngine should get the AST from the ASTProvider so it can profit if the AST is already cached (2 occurences) e.g. JaavPlugin.getDefault().getASTProvider().getAST(cu)
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/search/FindOccurrencesEngine.java
for (int i = 0; i < markers.length; i++) {
					IMarker marker= markers[i];
					Map attributes= marker.getAttributes();
					addSpecialAttributes(attributes);
					marker.setAttributes(attributes);
					addMatch(view, file, marker);
				}
				searchFinished(view);
			}
		};
		run(runnable);
		return null;
	}
	private ISearchResultView startSearch() {
		SearchUI.activateSearchResultView();
		ISearchResultView view= SearchUI.getSearchResultView();
		IJavaElement element= getInput();
		if (view != null) {
			fFinder.searchStarted(view, element.getElementName());
		}
		return view;
	}
	
	private void addMatch(final ISearchResultView view, IResource file, IMarker marker) {
		if (view != null)
			view.addMatch("", getGroupByKey(marker), file, marker); 
	}
	
	private void searchFinished(final ISearchResultView view) {
		if (view != null)