Bug 165172 [EFS] FileEditorInput should implement IURIEditorInput
Now that we have IURIEditorInput, we should change IFileEditorInput to implement this interface.
bundles/org.eclipse.ui.ide/extensions/org/eclipse/ui/part/FileEditorInput.java
*/
	public Object getAdapter(Class adapter) {
		if (adapter == IFile.class) {
			return file;
		}
		return file.getAdapter(adapter);
	}
	/* (non-Javadoc)
	 * Method declared on IPersistableElement.
	 */
	public String getFactoryId() {
		return FileEditorInputFactory.getFactoryId();
	}
	/* (non-Javadoc)
	 * Method declared on IFileEditorInput.
	 */
	public IFile getFile() {
		return file;
	}
	/* (non-Javadoc)
	 * Method declared on IEditorInput.
	 */
	public ImageDescriptor getImageDescriptor() {
		IContentType contentType = IDE.getContentType(file);
		return PlatformUI.getWorkbench().getEditorRegistry()
				.getImageDescriptor(file.getName(), contentType);
	}
	/* (non-Javadoc)
	 * Method declared on IEditorInput.
	 */