getEditorPositionFromNode(spanDomNode) {
        if (!spanDomNode || spanDomNode.children.length > 0) {
            // This is not a leaf node
            return null;
        }
        const renderedStickyLine = this._getRenderedStickyLineFromChildDomNode(spanDomNode);
        if (!renderedStickyLine) {
            return null;
        }
        const column = getColumnOfNodeOffset(renderedStickyLine.characterMapping, spanDomNode, 0);
        return new Position(renderedStickyLine.lineNumber, column);
    }
Given a leaf dom node, tries to find the editor position.